Caregivers' mental distress and child health during the COVID-19 outbreak in Japan.

To clarify the physical and mental conditions of children during the coronavirus disease 2019 pandemic and consequent social distancing in relation to the mental condition of their caregivers. This internet-based nationwide cross-sectional study was conducted between April 30 and May 13, 2020. The participants were 1,200 caregivers of children aged 3-14 years. Child health issues were categorized into "at least one" or "none" according to caregivers' perception. Caregivers' mental status was assessed using the Japanese version of the Kessler Psychological Distress Scale-6. The association between caregivers' mental status and child health issues was analyzed using logistic regression models. Among the participants, 289 (24.1%) had moderate and 352 (29.3%) had severe mental distress and 69.8% of children in their care had health issues. The number of caregivers with mental distress was more than double that reported during the 2016 national survey. After adjusting for covariates, child health issues increased among caregivers with moderate mental distress (odds ratio 2.24, 95% confidence interval 1.59-3.16) and severe mental distress (odds ratio 3.05, 95% confidence interval 2.17-4.29) compared with caregivers with no mental distress. The results highlight parents' psychological stress during the pandemic, suggesting the need for adequate parenting support. However, our study did not consider risk factors of caregivers' mental distress such as socioeconomic background. There is an urgent need for further research to identify vulnerable populations and children's needs to develop sustainable social support programs for those affected by the outbreak.

Introduction

There are various ways in which the coronavirus disease 2019 (COVID-19) pandemic and consequent lockdown and social distancing measures have placed strain on the physical and psychological health of children and adolescents [1]. Parental fear of visiting health facilities has led to a reduction in vaccination rates and necessary health care visits [1, 2]. School closures have resulted in isolation of children and families, increased their stress, and increased children’s risk of maltreatment at home [1, 3, 4]. In this already unprecedented situation, parental mental health problems related to fear of infection, economic pressure, and rapid changes in lifestyle are a major cause of concern [5]. However, the social distancing measures in place make it difficult to identify at-risk children and families who may be in need of social support. Children are also missing out on opportunities to study, exercise, and communicate with their peers and teachers, which are essential for healthy development [4].

In Japan, the social isolation measures instituted in response to an increasing number of COVID-19 cases included school closure between March and June, 2020 [6]. On April 7, the government declared a state of emergency, which was extended to the entire nation on April 16 and ultimately lifted on May 25 [7, 8]. During this period, people were asked to avoid unnecessary gatherings and outings without legal restrictions. Public health services for children and childrearing families—such as child health checkups, childrearing consultations for parents, school counseling for children, and social support for children with developmental disorders or disabilities—were also canceled during this period.

Regardless of increasing global awareness of child health concerns related to the pandemic and social isolation, surveys that clarify the actual situation of children and their families under the state of emergency in Japan are yet to be conducted. Therefore, the present study aimed to clarify the physical and psychological conditions of children and caregivers during the COVID-19 pandemic. Furthermore, we examined the association between caregivers’ mental status and the physical and psychological condition of children, which is particularly significant at a time when families were isolated and children spent most of their time at home.

Materials and methods

This study was approved by the Ethics Review Board of the University of Yamanashi (approval number: 2259). Informed consent was obtained via online.

Design and setting

This internet-based cross-sectional study was performed between April 30 and May 13, 2020. The Prime Minister requested school closure on February 29 and many schools and childcare facilities remained closed until the lifting of the state of emergency.

Participants

The target population was caregivers of children aged 3–14 years who had voluntarily registered with the Nippon Research Center as monitors for web-based surveys in response to online affiliate advertising. Eligible individuals were asked to participate in the survey through the center and only those who answered screening questions and provided their consent on the website answered the entire questionnaire. Data collection continued until the sample size reached 1,200. The sample size was calculated to detect a 20% absolute difference in the percentage of children with any physical or mental health problems between caregivers with and without mental distress based on reports of a 40–50% prevalence of mental distress in the general population during the pandemic.

Data collection

The internet-based questionnaire consisted of 35 questions related to participants and their children. The questionnaire was developed by the authors. No validation test was performed prior to the survey. However, the Japanese version of the Kessler Psychological Distress Scale-6 (K6), which was included in the questionnaire, has proven validity in the context of mental health screening [9]. The Cronbach’s alpha coefficient of the K6 score in this study was 0.93.

Participant-related questions included job type, time spent with the child, COVID-19-related concerns, and mental health status. Mental health status was assessed using the Japanese version of the K6 [9, 10]. The K6 has demonstrated excellent internal consistency and reliability [11] and is widely used in epidemiological studies [12]. The properties of the Japanese version are comparable to those of the original (the area under the receiver operating characteristic curve was 0.94 (95% confidence interval [CI] = 0.88 to 0.99) [9], and this tool has been used to screen for depression and anxiety disorders in the workplace and in the Comprehensive Survey of Living Conditions in Japan [13]. Questions about the child included whether the school/nursery was open, frequency of playing outside, screen time, and health condition as perceived by the participant.

Data collection was commissioned by the Nippon Research Center. If participants had more than one child, they were asked to restrict their answers to one child, who was randomly selected by the system.

Exposure

The main exposure was caregivers’ mental status, assessed using the Japanese version of the K6 [9]. Based on previous studies conducted in Japan, the K6 score was categorized into three groups: 0–4 (no mental distress), 5–9 (moderate mental distress), and ≥ 10 (severe mental distress) [9, 14].

Outcome

The primary outcome was child health condition as perceived by the participant. Child health status was measured by asking participants whether their child had at least one problem related to sleep, appetite, physical and mental conditions, activity, or behavior at the time of the survey. Sleep issues included difficulty in sleeping or waking up and disturbance of sleep rhythm. Appetite included both increased or reduced appetite and change in body weight and body image. Physical and mental conditions included dullness, fatigue, lack of energy, pale appearance, headaches, stomach aches, dizziness, and nausea. Activity was measured in terms of whether a child was reluctant to go out or meet friends. Behavior included repetitive actions, use of violence, being distracted, reduced emotional reactions, incoherent conversation, and a higher frequency of talking to oneself. Participants were asked to choose all applicable conditions.

Covariates

The covariates were the caregiver’s gender and age, child’s gender and age, geographical area of residence, whether the nursery/school was open at the time of the survey, child’s frequency of playing outside, child’s screen time, and time spent with the child during the daytime by both caregiver and partner. The child’s screen time included the use of any device for any purpose, including home schooling. The family’s socioeconomic status has previously been reported to be a risk factor for child mental health problems [5, 15, 16], and the questionnaire therefore asked about the respondents’ job type and their partners. We categorized the job type into employed/self-employed, part-time, and unemployed/housewife/student. However other potential risk factors for child mental health problems such as educational attainment [15, 16] and past medical history [16] were not included in the questionnaire, owing to the sensitivity of these topics and with a view to increasing the response rate.

Data analysis

The distribution of each variable was analyzed and summarized as number (%) or mean (standard deviation) as appropriate. A univariate analysis was then performed to analyze the association between child health and the caregiver’s mental status (K6 score) and each of the other covariates using logistic regression models. A multivariate analysis was performed to evaluate the association between the caregiver’s mental status and child health by adjusting for all covariates in the logistic regression models. Finally, interactions between the effects of the caregiver’s mental status and the caregiver’s gender, caregiver’s age, child’s gender, child’s age, and school closure on child health conditions were analyzed using likelihood ratio tests, as age and gender are important factors in determining children’s vulnerability to environmental change, such as the COVID-19 outbreak, according to previous studies [15, 16]. STATA/MP 16.1 software was used for all analyses.

Results

The Nippon research center requested a total of 2792 people to answer the questionnaire. Among 1748 people who answered screening questions, 548 people were removed because they did not meet eligibility criteria (caregivers of children aged 3–14 years). Table 1 summarizes the characteristics of the participants. Among 1,200 participants, 289 (24.1%) had moderate mental distress (K6 score of 5–9) and 352 (29.3%) had severe mental distress (K6 score of ≥ 10). Approximately half of the participants were male (51.1%) and about half resided in a city with more than 300,000 people. Half of the children were male (52.7%), and the majority were school-aged (75.0%). At the time of the survey, the schools/nurseries of the children of 75.5% of the participants were closed, while in the case of 15.4% of the participants, the children had access to either online classes or special offline classes. There were no missing data.

Table 1

Characteristics of study participants (N = 1,200).

Variable	n (%)
Participant’s mental distress (K6 score)
None (0–4)	559 (46.6)
Moderate (5–9)	289 (24.1)
Severe (≥ 10)	352 (29.3)
Participant’s gender
Male	613 (51.1)
Female	587 (48.9)
Participant’s age (years)
< 34	123 (10.3)
35–39	277 (23.1)
40–45	332 (27.7)
≥ 45	468 (39.0)
Participant’s job
Employed/self-employed	732 (61.0)
Part-time	184 (15.3)
Unemployed/housewife/student	284 (23.7)
Partner’s job
Employed/self-employed	725 (60.4)
Part-time	217 (18.1)
Unemployed/housewife/student	258 (21.5)
Size of city of residence (population)
< 50,000	143 (11.9)
50,000–100,000	162 (13.5)
100,000–300,000	299 (24.9)
300,000–500,000	196 (16.3)
≥ 500,000	400 (33.3)
Time spent with the child during daytime (participant)
All day	555 (46.2)
Half a day	217 (18.1)
Negligible	428 (35.7)
Time spent with the child during daytime (partner)
All day	433 (36.1)
Half a day	234 (19.5)
Negligible	533 (44.4)
Number of children
1	376 (31.3)
2	646 (53.8)
≥ 3	178 (14.8)
Child’s gender
Male	632 (52.7)
Female	568 (47.3)
Child’s age (years)
3–5	300 (25.0)
6–12	700 (58.3)
≥ 13	200 (16.7)
Status of nursery/school
Open	109 (9.1)
Online classes/open for children in need	185 (15.4)
Closed	906 (75.5)
Frequency of playing outside
Almost every day	179 (14.9)
3–5 days per week	291 (24.3)
1–2 days per week	323 (26.9)
Almost never	407 (33.9)
Screen time compared to before outbreak
None	162 (13.5)
Less	33 (2.8)
Same	307 (25.6)
Double	363 (30.3)
More than triple	335 (27.9)

Table 2 depicts the frequency of child health issues. The children of 69.8% of the participants had at least one health-related issue. The most frequent issue was change in sleep rhythm (57.3%), followed by change in appetite (28.4%).

Table 2

Child health issues reported by participants (N = 1,200).

Variable	n (%)
Child health issues (overall)
None	362 (30.2)
At least one	838 (69.8)
Sleep rhythm change
No	512 (42.7)
Yes	688 (57.3)
Appetite change
No	859 (71.6)
Yes	341 (28.4)
Physical/mental conditions
No	1,068 (89.0)
Yes	132 (11.0)
Activity
No	1,000 (83.3)
Yes	200 (16.7)
Behavior change
No	1,066 (88.8)
Yes	134 (11.2)

Table 3 summarizes the crude and adjusted odds ratios (ORs) of child health issues in relation to participants’ mental health status. The univariate analyses showed that moderate and severe mental distress in participants was associated with increased odds of their child experiencing health issues (moderate distress: OR 2.27, 95% CI 1.64–3.12, OR 2.86, 95% CI 2.09–3.91) compared with no mental distress. Furthermore, regarding the children, higher age, nursery/school being closed, lower frequency of playing outside, and increased screen time were associated with health issues. After adjusting for covariates, participants’ mental status was still associated with child health issues. Odds of child health issues were higher among participants with moderate mental distress (OR 2.24, 95% CI 1.59–3.16) and severe mental distress (OR 3.05, 95% CI 2.17–4.29), compared with those with no mental distress. Increased screen time was also associated with child health issues in the adjusted model. There was no interaction between the effects of the caregiver’s mental status and caregiver’s gender (p = 0.773), caregiver’s age (p = 0.110), child’s gender (p = 0.342), child’s age (p = 0.738), and school closure (p = 0.437) on child health condition.

Table 3

Crude and adjusted odds ratios of child health issues in relation to caregivers’ mental status and other covariates (N = 1,200).

	Crude OR	Adjusted OR1
Participant’s mental distress (K6 score)
None (0–4)	1.00	1.00
Moderate (5–9)	2.27 (1.64–3.12)	2.21 (1.56–3.12)
Severe (≥ 10)	2.86 (2.09–3.91)	3.11 (2.21–4.39)
Time spent with the child during daytime (participant)
All day	1.00	1.00
Half a day	0.86 (0.61–1.22)	0.98 (0.63–1.50)
Negligible	0.66 (0.50–0.87)	0.90 (0.62–1.33)
Time spent with the child during daytime (partner)
All day	1.00	1.00
Half a day	0.85 (0.60–1.20)	0.90 (0.59–1.39)
Negligible	0.87 (0.66–1.15)	0.80 (0.54–1.19)
Child’s gender
Male	1.00	1.00
Female	0.86 (0.67–1.10)	1.00 (0.76–1.32)
Child’s age (years)
3–5	1.00	1.00
6–12	1.60 (1.20–2.12)	1.14 (0.78–1.66)
≥ 13	2.00 (1.34–2.98)	1.30 (0.76–2.22)
Status of nursery/school
Open	1.00	1.00
Online classes/open for children in need	1.91 (1.17–3.13)	1.04 (0.57–1.90)
Closed	1.96 (1.30–2.93)	1.18 (0.71–1.97)
Frequency of playing outside
Almost every day	1.00	1.00
3–5 days per week	1.17 (0.80–1.72)	0.85 (0.55–1.32)
1–2 days per week	1.77 (1.20–2.61)	1.41 (0.91–2.18)
Almost never	1.90 (1.30–2.76)	1.09 (0.70–1.70)
Screen time compared with before outbreak
None	1.00	1.00
Less	1.32 (0.62–2.81)	0.93 (0.42–2.09)
Same	1.48 (1.01–2.17)	1.37 (0.91–2.06)
Double	3.78 (2.55–5.61)	3.22 (2.10–4.93)
More than triple	6.44 (4.18–9.93)	5.60 (3.52–8.90)

OR: odds ratio

1Adjusted for all other variables in the table as well as participant’s gender, participant’s age, participant’s job, partner’s job, number of children, and size of city of residence.

Caregivers’ mental distress and increased screen time in children were associated with every aspect of child health issues: change in sleep, appetite, physical/mental condition, activity, and behavior (Table 4).

Table 4

Adjusted odds ratios of child health issues by subdomains (N = 1,200).

	Sleep rhythm change	Appetite change	Physical/mental conditions	Activity	Behavior change
Participant’s mental distress (K6 score)
None (0–4)	1.00	1.00	1.00	1.00	1.00
Moderate (5–9)	2.13 (1.56–2.91)	1.99 (1.43–2.76)	1.73 (1.02–2.93)	2.23 (1.50–3.31)	2.48 (1.48–4.16)
Severe (≥ 10)	2.65 (1.96–3.58)	1.79 (1.31–2.47)	3.44 (2.16–5.46)	1.69 (1.14–2.52)	3.84 (2.39–6.17)
Child’s age (years)
3–5	1.00	1.00	1.00	1.00	1.00
6–12	1.14 (0.80–1.61)	0.85 (0.58–1.25)	1.05 (0.57–1.93)	0.98 (0.60–1.59)	1.04 (0.60–1.82)
≥ 13	1.37 (0.84–2.22)	1.00 (0.60–1.67)	1.43 (0.68–3.02)	0.93 (0.50–1.73)	0.74 (0.35–1.59)
Status of nursery/school
Open	1.00	1.00	1.00	1.00	1.00
Online classes/open for children in need	1.48 (0.83–2.63)	1.65 (0.88–3.08)	3.09 (1.12–8.57)	1.46 (0.63–3.38)	1.19 (0.50–2.85)
Closed	1.20 (0.73–1.96)	1.15 (0.66–1.98)	1.45 (0.56–3.77)	1.23 (0.58–2.58)	0.73 (0.33–1.59)
Frequency of playing outside
Almost every day	1.00	1.00	1.00	1.00	1.00
3–5 days per week	0.91 (0.60–1.36)	0.88 (0.57–1.38)	2.17 (0.84–5.59)	3.06 (1.48–6.34)	1.56 (0.79–3.07)
1–2 days per week	1.53 (1.02–2.29)	0.87 (0.56–1.36)	3.92 (1.58–9.72)	2.58 (1.24–5.37)	1.13 (0.57–2.25)
Almost never	1.37 (0.91–2.06)	0.91 (0.58–1.41)	4.50 (1.82–11.2)	4.23 (2.07–8.66)	1.29 (0.65–2.54)
Screen time compared to before outbreak
None	1.00	1.00	1.00	1.00	1.00
Less	1.06 (0.48–2.36)	1.41 (0.54–3.71)	1.32 (0.23–7.56)	0.68 (0.14–3.27)	1.21 (0.30–4.95)
Same	1.14 (0.76–1.72)	1.43 (0.84–2.42)	2.64 (0.97–7.19)	1.30 (0.64–2.64)	0.91 (0.39–2.14)
Double	2.16 (1.44–3.26)	2.85 (1.71–4.76)	3.41 (1.28–9.06)	2.15 (1.09–4.22)	2.11 (0.97–4.59)
More than triple	3.07 (2.01–4.68)	3.57 (2.14–5.96)	4.93 (1.86–13.0)	3.94 (2.04–7.63)	3.50 (1.64–7.47)

OR: odds ratio

Adjusted for all other variables in the table as well as participant’s gender, participant’s age, participant’s job, partner’s job, participant’s time spent with the child during daytime, partner’s time spent with the child during daytime, number of children, and size of city of residence.

Discussion

The present study revealed that the number of caregivers with moderate to severe mental distress during the state of emergency was more than double the number observed in national surveys, wherein the prevalence of moderate and severe mental distress among people aged 20 years and above was 18.9% and 10.5% in 2016, and 18.7% and 10.3% in 2019, respectively [13]. Globally, the COVID-19 pandemic has led to a surge in mental health issues in the general population owing to fear of infection, exposure to uncertain information, and stress associated with the economic recession [15, 17, 18]. According to a meta-analysis, the global prevalence of depression during the COVID-19 pandemic was 28% (23–32%) [15]. Although assessment tools have differed across studies, the reported prevalence rates have been similar to the present study (29.3% prevalence of severe mental distress) [15].

Previous studies have reported that the factors that increase psychological vulnerability to pandemics and disasters include female gender, lower socioeconomic status, interpersonal conflicts, frequent use of social media, inaccurate health information, lower resilience, lack of social support, and pre-existing physical and psychological symptoms [16, 17, 19]. As these risk factors were beyond the scope of this study, it was not possible to determine the reasons for increased mental distress in the study population. Nonetheless, it can be assumed that many people had no access to the necessary social support during the state of emergency because of the suspension of public services such as schools, health checkups, and parental classes. Moreover, many caregivers had to work at home while simultaneously caring for their children, which may have increased psychological stress [5]. Further studies are needed to identify vulnerable populations and develop support programs to prevent mental distress and consequent health problems.

Among the participants, 69.8% had children with at least one of the health issues in question. The national online survey of children’s quality of life and health during the COVID-19 pandemic conducted at the same time as the present study (between April 30 and May 5) reported that 39% of children felt uncomfortable when thinking of COVID-19 and more than 30% had difficulty concentrating or were easily irritable [20]. It is difficult to directly compare the results, as the two studies used differing terminology to assess different aspects of child health. Furthermore, the respondents differed (i.e., answers were provided by caregivers or children). However, the two studies suggested that children commonly experienced stress during the pandemic and presented unpleasant reactions such as anxiety, irritability, and difficulty in sleep. It is important to follow up on whether those conditions have remained, increased, or decreased with the easing of COVID-19-related restrictions, and to determine what factors can mitigate adverse child health conditions. The present study showed that mental distress among caregivers was associated with an increased risk of child health issues. This result is consistent with previous studies reporting a relationship between parental mental health problems and behavioral and physiological problems in their offspring [21-24]. It is known that children and adolescents are particularly vulnerable to stress in the aftermath of natural disasters, owing to their cognitive and psychological immaturity [25]; therefore, they need adult support to adjust to their changed circumstances. In this context, family discordance shortly after a natural disaster could lead to poor mental health and disruptive behavior among children [26]. In particular, the closure of schools and suspension of public health services increased the importance of family functioning during the pandemic. However, given the increased stress of caregivers and the strong association between caregivers’ mental distress and child health issues, it would be difficult to rely solely on parents to support and care for children. The development of measures to support isolated families and children during the pandemic is very important.

Another remarkable finding was that in 58.2% of children, screen time was more than double compared to before the pandemic. Although the advantages of using multimedia devices during the pandemic have been acknowledged [27], increased screen time in the present study may have been associated with recreational purposes, given that only 15.4% of children had access to online classes. This increase in recreational usage might be a result of the disturbance in daily routine because of the closure of nurseries/schools and limited opportunities for outdoor play. This may also suggest limited parental disciplinary ability with regard to ensuring that children adhered to their regular routine during the period of school closure. This increase was associated with a rise in overall child health issues and problems related to sleep, appetite, physical/mental condition, activity, and behavior, independent of the caregiver’s mental status. The negative associations between excessive screen time and sleep and mental health problems have also been reported in previous studies [28, 29]. As heavy usage is potentially detrimental to children’s physical and psychological health, social connectedness, and academic performance [30], it is necessary to limit children’s screen time to help them adhere to routines, engage in healthy activities, and communicate with others.

The present study had several limitations. Owing to the cross-sectional design, the possibility of reverse causation between caregivers’ mental health and child health issues cannot be eliminated. In addition, it was difficult to determine whether caregivers’ mental distress existed before the pandemic or resulted from it. Data on chronological trends in child health issues were not available either. However, given the stable prevalence of mental distress in the 2016 and 2019 surveys, it would be reasonable to consider that the pandemic influenced the increased prevalence of mental distress among caregivers in the present study. Future studies must compare changes in child health issues before and after the pandemic and determine how long the issues persisted after the lifting of the state of emergency. Additionally, the present study did not consider social factors such as family income and participants’ physical and psychological background, which have been reported to be risk factors for mental distress during the COVID-19 pandemic [15, 16]. Further studies considering these factors will be necessary to identify vulnerable populations and to provide customized support for them. Finally, as the examination of child health status was not based on self-reports, caregivers’ mental status may have influenced their responses [31]. Therefore, the reported prevalence of child health issues might not reflect the real situation. In addition, the questionnaire did not reflect children’s perspectives. Future studies should address the real situation and needs of children by employing self-reports; this information is essential for the provision of effective child-centered support.

Conclusion

This study is the first to investigate mental health issues in caregivers and their association with child health during the COVID-19 outbreak in Japan. The results showed a tremendous increase in mental distress among caregivers and a strong association between caregivers’ mental distress and child health issues. These findings highlight the difficulties faced by caregivers in supporting children. They also suggest the importance of social support for families with children to protect their physical and psychological health during the outbreak. However, both formal and informal social support for children and their families during the state of emergency was quite limited in Japan and caregivers did not have much assistance in caring for their children. There is an urgent need for further research to identify vulnerable populations and children’s needs to develop feasible and sustainable social support initiatives specific to infectious outbreaks.

Original survey questionnaire (Japanese).

(DOCX)

Click here for additional data file.

Survey questionnaire translated in English.

(DOCX)

Click here for additional data file.

Minimal anonymized data.

(XLSX)

Click here for additional data file.

29 Oct 2020

PONE-D-20-28599

Caregivers’ mental distress and child health during the COVID-19 outbreak in Japan

PLOS ONE

Dear Dr. Horiuchi,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

The two reviewers addressed several major and minor concerns about your manuscript. Please revise your manuscript carefully.

Please submit your revised manuscript by Dec 13 2020 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.

A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

We look forward to receiving your revised manuscript.

Kind regards,

Kenji Hashimoto, PhD

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. Please include additional information regarding the survey or questionnaire used in the study and ensure that you have provided sufficient details that others could replicate the analyses. For instance, if you developed a questionnaire as part of this study and it is not under a copyright more restrictive than CC-BY, please include a copy, in both the original language and English, as Supporting Information.  If the original language is written in non-Latin characters, for example Amharic, Chinese, or Korean, please use a file format that ensures these characters are visible.

3. Please state whether you validated the questionnaire prior to testing on study participants. Please provide details regarding the validation group within the methods section.

4.We note that you have indicated that data from this study are available upon request. PLOS only allows data to be available upon request if there are legal or ethical restrictions on sharing data publicly. For information on unacceptable data access restrictions, please see http://journals.plos.org/plosone/s/data-availability#loc-unacceptable-data-access-restrictions.

In your revised cover letter, please address the following prompts:

a) If there are ethical or legal restrictions on sharing a de-identified data set, please explain them in detail (e.g., data contain potentially identifying or sensitive patient information) and who has imposed them (e.g., an ethics committee). Please also provide contact information for a data access committee, ethics committee, or other institutional body to which data requests may be sent.

b) If there are no restrictions, please upload the minimal anonymized data set necessary to replicate your study findings as either Supporting Information files or to a stable, public repository and provide us with the relevant URLs, DOIs, or accession numbers. Please see http://www.bmj.com/content/340/bmj.c181.long for guidelines on how to de-identify and prepare clinical data for publication. For a list of acceptable repositories, please see http://journals.plos.org/plosone/s/data-availability#loc-recommended-repositories.

We will update your Data Availability statement on your behalf to reflect the information you provide.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: No

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: In this population-based epidemiological study, the authors aimed to clarify the physical and mental conditions of children during the coronavirus disease 2019 pandemic and consequent social distancing concerning the mental condition of their caregivers. The present study contributed to a more clear understanding of the influrence of the COVID-19 on caregivers’ mental status and child health issues.

I wish the authors can answer the following questions：

1. Please describe the process of questionnaire collection in detail. What kind of family registered ‘the Nippon Research Center’ before. How many people have received the invitation to participate? What is the response rate? Were all the questionnaires valid?

2. In your result, more than 1/3 caregivers can not spend much time with their children. Maybe the child's health problem is due to the parents' lack of companionship, but not the caregivers’ mental status. How to explain that they don't get along with their children frequently and affect their children's health at the same time.

3. Is it possible that some families have two or more children? Does this affect the result? Would they fill the questionnaire twice or more times？

4. The conclusion in the abstract is ambiguous. ‘The results highlight the infeasibility of parents being solely responsible for the care and support of children.’ But the data did not provide any relevant information to prove the children were only taken care of by parents.

5. Self-reported might be the only way to investigate in the period of COVID-19. The K-6 scale is relatively simple. I suggest the authors use the scale as a measurement but not as a definition of ‘depression’.

6. In the discussion, in 58.2% of children, screen time was more than double compared to before the pandemic . But in result 'in the case of 15.4% of the participants, the children had access to either online classes or special offline classes.' This indirectly means that many Internet users may be recreational. This should be discussed in detail.

7. In result Table 3 and 4, only 'OR' can be seen. Why there were no 'p'. values. How do we know if it's significant?

Reviewer #2: 1. Line 39. “infeasibility” is an intense word to use without being to state causation

2. Formatting is inconsistent throughout the manuscript (e.g., Odds ratios,

3. Need references for government declarations (i.e., line 50, 52, & 70)

4. Mental issues seems inappropriate (mental disorders or distress would be more appropriate (i.e., line 77 & 79)

5. What is the reliability of the Kessler Psychological Distress Scale-6? What was the alpha for this study?

6. Line 90 references a questionnaire developed by the authors but does not describe the questionnaire

7. It is unclear what the authors are referring to with the “exposure” section. What is an exposure?

8. Is it typical to not include questions due to concern about sensitivity? Seems like a big oversight to not ask about SES, education, or medical history

9. Line 128-129 “as age and gender are important factors…” needs a reference

10. Line 143 I believe it should be “there was no missing data”

11. Table 1 described the K6 as indicating participant’s mental status and this also seems inappropriate (mental distress or wellbeing would be more appropriate)

12. Line 187 this sentence is unclear and should b e re-written

13. Line 192 what vulnerability are you describing? (e.g., mental distress)

14. A lot of factors were missed described as beyond the scope of this study which seems to limit the utility of this study

15. Line 209 althought it may be difficult to compare with incommensurable measures I believe some comparison of the results could be further discussed.

16. Line 238 “owing” should be replaced with another word (e.g., due)

17. Line 243 seems to be a large assumption that the pandemic worsened caregivers mental health due to the results of this study as there is no data of their mental health prior to the pandemic

18. Formatting of references must be consistent (e.g., hyperlink)

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: Yes: Ashley A. Balsom

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

11 Nov 2020

Editor: We really appreciate your consideration for our study and valuable comments to improve it. Our response to each of the comments are as follows.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

Reply: We carefully have checked and followed the instructions to meet PLOS ONE’s style requirements.

2. Please include additional information regarding the survey or questionnaire used in the study and ensure that you have provided sufficient details that others could replicate the analyses. For instance, if you developed a questionnaire as part of this study and it is not under a copyright more restrictive than CC-BY, please include a copy, in both the original language and English, as Supporting Information. If the original language is written in non-Latin characters, for example Amharic, Chinese, or Korean, please use a file format that ensures these characters are visible.

Reply: We have attached the original questionnaire in Japanese (original) and English translation as supporting information.

“S1 File. Original survey questionnaire (Japanese)

S2 File. Survey questionnaire translated in English”

3. Please state whether you validated the questionnaire prior to testing on study participants. Please provide details regarding the validation group within the methods section.

Reply: We did not validate the questionnaire prior to the survey. The Japanese version of the Kessler Psychological Distress Scale-6 (K6), which was included in the questionnaire, has proven valid. We have added details in the methods section as follows:

(lines 86-90) “The questionnaire was developed by the authors. No validation test was performed prior to the survey. However, the Japanese version of the Kessler Psychological Distress Scale-6 (K6), which was included in the questionnaire, has proven validity in the context of mental health screening.9 The Cronbach’s alpha coefficient of the K6 score in this study was 0.93.”

4.We note that you have indicated that data from this study are available upon request. PLOS only allows data to be available upon request if there are legal or ethical restrictions on sharing data publicly. For information on unacceptable data access restrictions, please see http://journals.plos.org/plosone/s/data-availability#loc-unacceptable-data-access-restrictions.

Reply: There are no legal or ethical restrictions on sharing data, and we would like to share the data publicly.

In your revised cover letter, please address the following prompts:

a) If there are ethical or legal restrictions on sharing a de-identified data set, please explain them in detail (e.g., data contain potentially identifying or sensitive patient information) and who has imposed them (e.g., an ethics committee). Please also provide contact information for a data access committee, ethics committee, or other institutional body to which data requests may be sent.

b) If there are no restrictions, please upload the minimal anonymized data set necessary to replicate your study findings as either Supporting Information files or to a stable, public repository and provide us with the relevant URLs, DOIs, or accession numbers. Please see http://www.bmj.com/content/340/bmj.c181.long for guidelines on how to de-identify and prepare clinical data for publication. For a list of acceptable repositories, please see http://journals.plos.org/plosone/s/data-availability#loc-recommended-repositories.

Reply: We have attached the minimal anonymized data set as supporting information. Consent for publication of raw data not obtained but dataset is fully anonymous in a manner that can easily be verified by any user of the dataset. Publication of the dataset clearly and obviously presents minimal risk to confidentiality of study participants. This statement has been included in the revised cover letter.

1. Thank you for including your ethics statement on the online submission form: "This study was approved by the Ethics Review Board of the University of Yamanashi (approval number: 2259). Informed consent was obtained via online.".

To help ensure that the wording of your manuscript is suitable for publication, would you please also add this statement at the beginning of the Methods section of your manuscript file.

Reply: We appreciate your suggestion and have included the ethics statement in the Methods section.

(line 67-68) “This study was approved by the Ethics Review Board of the University of Yamanashi (approval number: 2259). Informed consent was obtained via online.”

Reviewer #1: We appreciate your valuable comments to improve our study, and accordingly have attempted to address all of your concerns, as below.

Reviewer #1: In this population-based epidemiological study, the authors aimed to clarify the physical and mental conditions of children during the coronavirus disease 2019 pandemic and consequent social distancing concerning the mental condition of their caregivers. The present study contributed to a more clear understanding of the influence of the COVID-19 on caregivers’ mental status and child health issues.

I wish the authors can answer the following questions：

1. Please describe the process of questionnaire collection in detail. What kind of family registered ‘the Nippon Research Center’ before. How many people have received the invitation to participate? What is the response rate? Were all the questionnaires valid?

Reply: We appreciate your valuable suggestions. Registration to the Nippon Research Center is done on voluntary basis through online affiliate advertising. The Nippon research center requested 2792 people to answer the questionnaire, and 1200 people who answered the entire questionnaire were included in this study. While the questionnaire that was developed by the authors were not validated prior to the survey, the Japanese version of the Kessler Psychological Distress Scale-6 (K6), which was included in the questionnaire, has proven valid. We have added explanation in the method and result sections as follows.

(lines 74-78) “The target population was caregivers of children aged 3–14 years who had voluntarily registered with the Nippon Research Center as monitors for web-based surveys in response to online affiliate advertising. Eligible individuals were asked to participate in the survey through the center and only those who answered screening questions and provided their consent on the website answered the entire questionnaire.”

(line 86-90) “The questionnaire was developed by the authors. No validation test was performed prior to the survey. However, the Japanese version of the Kessler Psychological Distress Scale-6 (K6), which was included in the questionnaire, has proven validity in the context of mental health screening.9 The Cronbach’s alpha coefficient of the K6 score in this study was 0.93.”

(lines 101-103) “Data collection was commissioned by the Nippon Research Center. If participants had more than one child, they were asked to restrict their answers to one child, who was randomly selected by the system.”

(lines 148-151) “The Nippon research center requested a total of 2792 people to answer the questionnaire. Among 1748 people who answered screening questions, 548 people were removed because they did not meet eligibility criteria (caregivers of children aged 3–14 years).”

2. In your result, more than 1/3 caregivers cannot spend much time with their children. Maybe the child's health problem is due to the parents' lack of companionship, but not the caregivers’ mental status. How to explain that they don't get along with their children frequently and affect their children's health at the same time.

Reply: In fact, respondent’s time spent with the child during daytime was inversely associated with child health issue in univariate analysis and the association disappeared in multivariate analysis. Partner’s time spent with the child during daytime was not associated with child health issue either in univariate or multivariate analyses. Therefore, we included time spent with the child in multivariate analyses but did not present its effect estimates in Table 3. We now have included the results (effect estimates of time spent with the child) in Table 3 in the revised manuscript. Caregivers’ mental distress was still associated with child health issue after adjusting for respondent’s and partner’s time spent with the child during daytime.

3. Is it possible that some families have two or more children? Does this affect the result? Would they fill the questionnaire twice or more times？

Reply: As you pointed out, about 70% of the respondents had more than two children. The respondent answered the questionnaire only once regarding one of their children who was randomly selected by the system. The choice of the child was explained as follows in the method section.

(lines 101-103) “If participants had more than one child, they were asked to restrict their answers to one child, who was randomly selected by the system.”

We have added the number of children in the multivariate analysis (Tables 3 and 4). The number of children was not associated with child health issue. It did not influence on the association between child health issue and respondent’s mental status (K6 score) either.

4. The conclusion in the abstract is ambiguous. ‘The results highlight the infeasibility of parents being solely responsible for the care and support of children.’ But the data did not provide any relevant information to prove the children were only taken care of by parents.

Reply: We greatly appreciate your points to improve our manuscript. We have revised the part as follows:

(lines 29-31) “The results highlight parents’ psychological stress during the pandemic, suggesting the need for adequate parenting support.”

5. Self-reported might be the only way to investigate in the period of COVID-19. The K-6 scale is relatively simple. I suggest the authors use the scale as a measurement but not as a definition of ‘depression’.

Reply: We agree on your point. We have deleted depression from the label of the K6 category. As the K6 has been utilized as a screening tool of depression and anxiety disorder in Japan, we would like to add the following explanation in the method section for readers.

(lines 94-98) “The properties of the Japanese version are comparable to those of the original (the area under the receiver operating characteristic curve was 0.94 (95% confidence interval [CI] = 0.88 to 0.99),9 and this tool has been used to screen for depression and anxiety disorders in the workplace and in the Comprehensive Survey of Living Conditions in Japan.13”

Reference 13. Ministry of Health, Labour and Welfare. Comprehensive Survey of Living Conditions [cited 2020 Jul 28]. Available from: https://www.mhlw.go.jp/toukei/saikin/hw/k-tyosa/k-tyosa16/dl/04.pdf

6. In the discussion, in 58.2% of children, screen time was more than double compared to before the pandemic. But in result 'in the case of 15.4% of the participants, the children had access to either online classes or special offline classes.' This indirectly means that many Internet users may be recreational. This should be discussed in detail.

Reply: We appreciate your insightful comment. We would like to discuss this point in detail as follows.

(lines 247-254) “Although the advantages of using multimedia devices during the pandemic have been acknowledged,28 increased screen time in the present study may have been associated with recreational purposes, given that only 15.4% of children had access to online classes. This increase in recreational usage might be a result of the disturbance in daily routine because of the closure of nurseries/schools and limited opportunities for outdoor play. This may also suggest limited parental disciplinary ability with regard to ensuring that children adhered to their regular routine during the period of school closure.”

7. In result Table 3 and 4, only 'OR' can be seen. Why there were no 'p'. values. How do we know if it's significant?

Reply: We did not include p-values as confidence intervals that do not cross 1 also suggest statistically significant association.

Reviewer #2: We appreciate your valuable comments to improve our study, and accordingly have attempted to address all of your concerns, as below.

1. Line 39. “infeasibility” is an intense word to use without being to state causation

Reply: We agree on your point. We have revised the part as follows:

(lines 29-31) “The results highlight parents’ psychological stress during the pandemic, suggesting the need for adequate parenting support.”

2. Formatting is inconsistent throughout the manuscript (e.g., Odds ratios,

Reply: We appreciate your suggestion. We would like to use “OR” throughout the main part and use “odds ratio” in the abstract to avoid abbreviation. We hope that it would be acceptable.

3. Need references for government declarations (i.e., line 50, 52, & 70)

Reply: We greatly appreciate your suggestion and have added government website in the reference list.

“6. Ministry of Education, Culture, Sports, Science and Technology. Information on MEXT’s measures against COVID-19 [cited 2020 October 31]. Available from: https://www.mext.go.jp/en/mext_00006.html

7. Prime Minister of Japan and His Cabinet. [COVID-19] Declaration of a State of Emergency in response to the Novel Coronavirus Disease (April 7) [cited 2020 October 31]. Available from: https://japan.kantei.go.jp/ongoingtopics/_00018.html

8. Prime Minister of Japan and His Cabinet. [COVID-19] The Declaration of the Lifting of the State of Emergency in Response to the Novel Coronavirus Disease [cited 2020 October 31]. Available from: https://japan.kantei.go.jp/ongoingtopics/_00027.html”

4. Mental issues seems inappropriate (mental disorders or distress would be more appropriate (i.e., line 77 & 79)

Reply: We agree on your suggestion and have revised the sentence as follows accordingly:

(lines 79-83) “The sample size was calculated to detect a 20% absolute difference in the percentage of children with any physical or mental health problems between caregivers with and without mental distress based on reports of a 40–50% prevalence of mental distress in the general population during the pandemic.”

5. What is the reliability of the Kessler Psychological Distress Scale-6? What was the alpha for this study?

Reply: The areas under receiver operating characteristic curves (AUC) was reported as 0.94 (95% confidence interval = 0.88 to 0.99) for K6 by Furukawa et al. (The performance of the Japanese version of the K6 and K10 in the World Mental Health Survey Japan, 2008). The scale reliability coefficient was 0.93 in the present study. We have added explanation as follows:

(lines 89-90) “The Cronbach’s alpha coefficient of the K6 score in this study was 0.93.”

(lines 94-98) “The properties of the Japanese version are comparable to those of the original (the area under the receiver operating characteristic curve was 0.94 (95% confidence interval [CI] = 0.88 to 0.99),9 and this tool has been used to screen for depression and anxiety disorders in the workplace and in the Comprehensive Survey of Living Conditions in Japan.13”

6. Line 90 references a questionnaire developed by the authors but does not describe the questionnaire

Reply: The contents of the questionnaire were described in lines 89-98. We have added the questionnaire (Japanese original version and English translation) in supporting information.

(lines 91-100) “Participant-related questions included job type, time spent with the child, COVID-19-related concerns, and mental health status. Mental health status was assessed using the Japanese version of the K6.9,10 The K6 has demonstrated excellent internal consistency and reliability11 and is widely used in epidemiological studies.12 The properties of the Japanese version are comparable to those of the original (the area under the receiver operating characteristic curve was 0.94 (95% confidence interval [CI] = 0.88 to 0.99),9 and this tool has been used to screen for depression and anxiety disorders in the workplace and in the Comprehensive Survey of Living Conditions in Japan.13 Questions about the child included whether the school/nursery was open, frequency of playing outside, screen time, and health condition as perceived by the participant.”

“Supporting information

S1 File. Original survey questionnaire (Japanese)

S2 File. Survey questionnaire translated in English”

7. It is unclear what the authors are referring to with the “exposure” section. What is an exposure?

Reply: The main exposure was caregivers’ mental status measured using the Japanese version of the K6.

8. Is it typical to not include questions due to concern about sensitivity? Seems like a big oversight to not ask about SES, education, or medical history

Reply: We agree that SES, educational status and medical history are important factors to consider in analyzing effects of mental distress of caregivers on child health issues during the pandemic. The survey was conducted in quite urgent manner to understand the situation of physical and psychological status and concerns of parents and children during the state of emergency period. Due to concern that some people might refrain answering the survey due to private questions, we had to omit some questions to maintain easiness to answer and raise the response rate. Nonetheless, we still asked about job type of respondents and their partners. We have included the job type in the analyses, which did not alter our conclusions. We would like to try to collect more data on SES and medical history in follow-up surveys.

(lines 126-133) “The family’s socioeconomic status has previously been reported to be a risk factor for child mental health problems,5,15,16 and the questionnaire therefore asked about the respondents’ job type and their partners. We categorized the job type into employed/self-employed, part-time, and unemployed/housewife/student. However other potential risk factors for child mental health problems such as educational attainment15,16 and past medical history16 were not included in the questionnaire, owing to the sensitivity of these topics and with a view to increasing the response rate.”

9. Line 128-129 “as age and gender are important factors…” needs a reference

Reply: References are attached as follows:

(lines 143-145) “….as age and gender are important factors in determining children’s vulnerability to environmental change, such as the COVID-19 outbreak, according to previous studies.15,16”

15. Luo M, Guo L, Yu M, Jiang W, Wang H. The psychological and mental impact of coronavirus disease 2019 (COVID-19) on medical staff and general public-a systematic review and meta-analysis. Psych Res 2020; 291:113190.

16. Vindegaard N, Eriksen Benros M. COVID-19 pandemic and mental health consequences: systematic review of the current evidence. Brain Behav Immun 2020. doi:10.1016/j.bbi.2020.05.048.

10. Line 143 I believe it should be “there was no missing data”

Reply: We appreciate your suggestion. An English editor have checked it again and confirmed that “Data” is always used in the plural. We would like to keep the original sentence: “There were no missing data.”

11. Table 1 described the K6 as indicating participant’s mental status and this also seems inappropriate (mental distress or wellbeing would be more appropriate)

Reply: We agree on your point and have revised the wording accordingly.

“Participant’s mental distress (K6 score): None (0–4), Moderate (5–9), Severe (≥ 10)”

12. Line 187 this sentence is unclear and should b e re-written

Reply: We have revised the sentence as follows. We hope this is readable and acceptable.

(lines 201-203) “Globally, the COVID-19 pandemic has led to a surge in mental health issues in the general population owing to fear of infection, exposure to uncertain information, and stress associated with the economic recession.”

13. Line 192 what vulnerability are you describing? (e.g., mental distress)

Reply: We appreciate your suggestion and have revised the sentence for more clarity as follows:

(lines 208-209) “Previous studies have reported that the factors that increase psychological vulnerability to pandemics and disasters”

14. A lot of factors were missed described as beyond the scope of this study which seems to limit the utility of this study

Reply: We appreciate your comments. The primary objective of the present study was to investigate the prevalence of mental distress among parents, the prevalence of health issues among children and the relationship between them. Therefore, we did not collect much data on characteristics of parents that can be risk factors of mental distress. Therefore, we could not consider what types of parents and households are at risk of mental distress during the outbreak in the present study. We believe that this would not influence the internal validity but the generalizability of our study. Further studies will be needed to understand more about those who are at risk of mental distress and in need of social support. It is explained in the limitation part as follows.

(lines 271-275) “Additionally, the present study did not consider social factors such as family income and participants’ physical and psychological background, which have been reported to be risk factors for mental distress during the COVID-19 pandemic.15,16 Further studies considering these factors will be necessary to identify vulnerable populations and to provide customized support for them.”

15. Line 209 althought it may be difficult to compare with incommensurable measures I believe some comparison of the results could be further discussed.

Reply: We appreciate your suggestion. While it is difficult to directly compare the prevalence of child health issues between the two studies, we have added consideration from the two studies as follows.

(lines 224-229) “It is difficult to directly compare the results, as the two studies used differing terminology to assess different aspects of child health. Furthermore, the respondents differed (i.e., answers were provided by caregivers or children). However, the two studies suggested that children commonly experienced stress during the pandemic and presented unpleasant reactions such as anxiety, irritability, and difficulty in sleep.”

17. Line 238 “owing” should be replaced with another word (e.g., due)

Reply: We appreciate your suggestion. An English editor have checked it again and confirmed that “owing to” is the best fit in this sentence. We would like to keep the original sentence.

(lines 262-264) “Owing to the cross-sectional design, the possibility of reverse causation between caregivers’ mental health and child health issues cannot be eliminated.”

17. Line 243 seems to be a large assumption that the pandemic worsened caregivers mental health due to the results of this study as there is no data of their mental health prior to the pandemic

Reply: We understand your point. The prevalence of the mental distress in the present study is tremendously higher compared to the national survey that evaluate the prevalence of mental distress using K6 every three years, which reported about 10% of severe mental distress constantly every time in previous 6 years. We consider that the dramatic change in the prevalence of mental distress between the time of survey and the present study would suggest the influence of the pandemic on mental health. We have added the results of 2019 national survey that are newly published. We have also revised the sentence as follows:

(lines 197-201) “The present study revealed that the number of caregivers with moderate to severe mental distress during the state of emergency was more than double the number observed in national surveys, wherein the prevalence of moderate and severe mental distress among people aged 20 years and above was 18.9% and 10.5% in 2016, and 18.7% and 10.3% in 2019, respectively.”

(lines 266-269) “However, given the stable prevalence of mental distress in the 2016 and 2019 surveys, it would be reasonable to consider that the pandemic influenced the increased prevalence of mental distress among caregivers in the present study.”

18. Formatting of references must be consistent (e.g., hyperlink)

Reply: We have reviewed the reference list and removed the hyperlink.

Submitted filename: Response to Reviewers.docx

Click here for additional data file.

27 Nov 2020

Caregivers’ mental distress and child health during the COVID-19 outbreak in Japan

PONE-D-20-28599R1

Dear Dr. Horiuchi,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Kenji Hashimoto, PhD

Section Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: N/A

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: (No Response)

Reviewer #2: I believe that the authors have thoughtfully and thoroughly addressed previous reviewer comments and am recommending that the manuscript be accepted.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

2 Dec 2020

PONE-D-20-28599R1

Caregivers’ mental distress and child health during the COVID-19 outbreak in Japan

Dear Dr. Horiuchi:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Prof. Kenji Hashimoto

Section Editor

PLOS ONE