Nasopharyngeal swabs vs. saliva sampling for SARS-CoV-2 detection: A cross-sectional survey of acceptability for caregivers and children after experiencing both methods.

BACKGROUND: Saliva sampling is a promising alternative to nasopharyngeal swabs for SARS-CoV-2 testing, but acceptability data is lacking. We characterize the acceptability of saliva sampling and nasopharyngeal swabs for primary decision makers and their children after experiencing both testing modalities.
METHODS: We administered a cross-sectional survey to participants aged 6-to-17 years and their primary decision makers at an Ottawa community COVID-19 testing centre in March 2021. Included were participants meeting local guidelines for testing. Excluded were those identified prior to participation as having inability to complete the consent, sampling, or survey process. Acceptability in multiple hypothetical scenarios was rated using a 5-point Likert scale. Pain was measured using the Faces Pain Scale-Revised (FPS-R). Preference for testing was assessed with direct binary questions.
RESULTS: 48 participants and 48 primary decision makers completed the survey. Nasopharyngeal swab acceptability differed between scenarios, ranging 79% [95%CI: 66, 88] to 100% [95%CI: 95, 100]; saliva sampling acceptability was similar across scenarios, ranging 92% [95%CI: 82, 97] to 98% [95%CI: 89, 99]. 58% of youth described significant pain with nasopharyngeal swabbing, versus none with saliva sampling. 90% of children prefer saliva sampling. 66% of primary decision makers would prefer nasopharyngeal swabbing if it were 10% more sensitive.
CONCLUSION: Though youth prefer saliva sampling over nasopharyngeal swabs, primary decision makers present for testing remain highly accepting of both. Acceptance of nasopharyngeal swabs, however, varies with the testing indication and is influenced by perceived test accuracy. Understanding factors that influence sampling acceptance will inform more successful testing strategies.

Introduction

Identification and isolation of individuals infected with SARS-CoV-2 are important components of the pandemic control effort [1, 2]. Using nasopharyngeal swabs for SARS-CoV-2 gene detection via reverse transcriptase polymerase chain reaction (RT-PCR) testing is the current criterion standard diagnostic test [3], but recent reviews of saliva sampling have identified this as a potential alternative [3, 4]. Saliva sampling potentially results in less discomfort and risk of viral transmission during testing, decreased utilization of personnel protective equipment, and reduced cost compared to nasopharyngeal swabs [5, 6]. Additionally, nasopharyngeal swabs are contra-indicated in some circumstances (eg. nasal anatomic pathology, coagulopathy) and have been associated with rare complications (eg. retained swabs, epistaxis, cerebrospinal fluid leakage) [7]. Saliva sampling by expectoration may not be possible for all patients, neonates for example, but saliva can also be sampled with an oral sponge. While pediatric data is under-represented in this literature, the presumption has been that SB sampling would be particularly preferable for children.

In a recent study, school-age children, parents and school personnel were offered COVID-19 surveillance via a saliva sampling method. They were then asked whether they would have consented to testing if a nasal swab was offered instead. Of those who accepted the saliva-based method, 36% would have refused a nasal swab [6]. Of note, more than half of the students in the study had never actually experienced a nasopharyngeal swab when answering the question.

To date there have been no studies comparing perceptions of saliva sampling and nasopharyngeal swabbing amongst children and caregivers who have undergone both sample collection methods. Their opinions could provide valuable insight into the factors affecting willingness to accept COVID-19 testing again in the future. Understanding how acceptable different sampling methods are to those making medical decisions for children, and under what circumstances, would inform future strategies for encouraging appropriate testing. The primary objective of this study was to characterize the acceptability of nasopharyngeal swabs and saliva sampling for COVID-19 in participants who have experienced both modalities. Test acceptability was defined as the willingness of the primary medical decision maker to accept a given test again, in a scenario where testing is indicated. Secondary objectives were to: 1) quantify pain from both saliva sampling and nasopharyngeal swabs; 2) determine which sampling modality was preferred by children; 3) evaluate how a perceived trade-off of test comfort versus accuracy would affect acceptability; and 4) evaluate the interest of primary decision makers for an intranasal topical numbing agent prior to nasopharyngeal swabbing.

Materials and methods

Approval for this study was granted by the Children’s Hospital of Eastern Ontario’s ethics review board.

Study design and setting

A cross-sectional survey was administered to a subset of participants enrolled in a parent study examining the accuracy of saliva testing for SARS-CoV-2 detection. Participants enrolled in the parent study voluntarily presented to an outpatient COVID-19 testing centre (Ottawa, Canada). This sub-study enrolled participants over 3 days in March 2021. Written informed consent was obtained from all participants or their primary decisions makers, and assent was obtained from children whose caregivers were consenting on their behalf.

Children 6 to 17 years old were eligible for inclusion if they: a) were a high-risk contact of a person confirmed to have COVID-19; b) travelled outside of Canada in the last 14 days; and/or c) had symptoms consistent with COVID-19 infection. Participants were excluded if they: i) did not consent to the parent study (which used both saliva and nasopharyngeal swab testing); ii) had a known developmental delay or intellectual disability that precluded completion of the survey; iii) had nasopharyngeal anomalies, iv) had been previously enrolled in the study; or v) there was a language barrier preventing informed consent.

Study procedure

Children and caregivers presenting to the regional COVID-19 test centre who consented to the parent study were offered participation in the present sub-study. As part of the parent study, participants underwent both a nasopharyngeal swab and a saliva sample. Nasopharyngeal swabs were inserted into the nasopharynx and gently rotated for 5 to 10 seconds. Saliva samples were collected via 2 different methods based on age. Children 6 to 8 years old had their saliva tested by a sponge-based kit (DNA Genotek; ORE-100). A small sponge was inserted between their cheek and teeth for 1 minute. Children 9 years and older were asked and encouraged to expectorate 1ml of saliva in a tube (DNA Genotek; OM-505). Once both samples were collected by nursing staff, a team member (FG, SH) administered a 15-item questionnaire to the children and their primary decision makers (for medical decisions). Adolescents (12 years old and older) could identify as being their own primary medical decision makers.

As no validated tool to assess our primary outcome existed, we developed a survey according to principles in the Association for Medical Education in Europe (AMEE) guide to questionnaire development [8]. The survey was piloted in families representative of the target population to ensure readability, sensibility and face and content validity. Three hypothetical clinical scenarios were developed to assess acceptability of both tests in different contexts: 1) The study participant requires testing in order to return to school; 2) The study participant has fever and cough and testing is recommended by a health care professional; 3) The study participant is a close contact of someone with COVID-19, but remains asymptomatic. Primary decision makers rated their willingness to accept a test on a 5-point Likert scale (“Very unlikely to Very likely”, see Supporting Information S1 File). Procedural pain was assessed using the validated Faces Pain Scale-Revised (FPS-R) [9]. Participants’ preference for sampling modality was assessed by asking them to indicate which they would choose if a future test was required, and the desire for an intranasal numbing agent was assessed with a yes or no question. Additionally, primary decision makers were asked to consider a potential trade-off of test comfort versus test sensitivity by indicating their test preference in a hypothetical scenario where saliva sampling was 10% less sensitive than a nasopharyngeal swab.

The survey was administered using an electronic device via secure online database (REDCap) [10]. Demographic information was obtained through linkage with the parent study database.

Statistical methods

To facilitate data analysis, answers to the 5-point Likert were dichotomized to likely and unlikely (including neutral answers). This decision was made during the initial data analysis, with the analyst blinded to any associations with the diagnostic test, as per best practice [11].

Descriptive statistics were calculated for continuous and categorical variables, as medians (with IQR) and frequencies (with proportions), respectively. We compared the proportions of participants answering they were likely to want a test in the 3 clinical scenarios based on which test was offered to them. The estimated proportions and corresponding 95% confidence interval (CI) for pain/preference between clinical scenarios were calculated using the Wilson’s score interval. We conducted an exploratory sub-group analysis on age (<12 vs. > = 12 years) to better understand the effect of age on the various outcomes. We also carried out an exploratory post-hoc analysis on the effect of the saliva sampling method (expectoration vs. sponge) on outcomes.

We determined a convenience sample size of 50 participants. Data were analyzed with SPSS (version 23; IBM, Armonk, NY).

Results

Patient characteristics

Fifty patients were enrolled in the study. Following enrolment, 2 participants were found to be ineligible due to their age. Forty-eight eligible patients were included in the analysis with a median age of 10 years (IQR: 9, 13). Clinical characteristics are presented in Table 1. All participants enrolled in the study were able to complete both sampling methods and answer the survey.

Table 1

Demographics.

Participants, N	48
Age, years (Median + [IQR])	10 [9,13]
Sex, female (N + [%])	24 [50%]
Saliva sampling method (N + [%])
Sponge	8 [17%]
Spit	40 [83%]
NP Swabs before this visit, yes (%)	23 [48%]
# NP Swabs for participants (Median + [IQR])	1 [1,3]
Primary decision maker NP Swabs, yes (N +[%])	27 [57%]
# NP swabs for primary decision maker (Median + [IQR])	1 [0,2]
Symptoms, yes (N + [%])	18 [38%]
Fever	5 [10%]
Respiratory	2 [4%]
Nasopharyngeal	9 [19%]
Gastroenterologic	11 [23%]
Non-specific	11 [23%]
Exposure to COVID contact, yes (N + [IQR])	31 [65%]
Primary decision maker education level (N + [%])
Less than high school	1 [2%]
High school	1 [2%]
College/Trade school/ CEGEP	15 [31%]
University	31 [65%]

Abbreviations: N = number, IQR = interquartile range, NP = Nasopharyngeal.

Main results

In the scenario in which their child required COVID-19 testing in order to return to school, almost all primary decision makers stated they would be likely to get their child tested independent of the offered sampling modality (98% [95%CI: 89, 99] for saliva method; 100% [95%CI: 95, 100] for nasopharyngeal swab; mean difference 2% [95%CI: -6, 10]; (Fig 1). In the scenario in which their child had a fever and a health care professional recommended testing, most primary decision makers stated they would be likely to get their child tested (98% [95%CI: 89, 99]) for saliva method; 94% [95%CI: 83, 98] for nasopharyngeal swab; mean difference 4% [95%CI: -6, 15]. In the scenario in which their child was in contact with someone who tested positive for COVID, but their child was asymptomatic, more primary decision makers would have their child tested by saliva sampling vs. nasopharyngeal swabs, but the difference was not statistically significant (92% [95%CI: 82, 97] for saliva method; 79% [95%CI: 66, 88]) for nasopharyngeal swab; mean difference 12.5% [95% CI: -1.9, 26].

Fig 1

Percentage of participants responding they would be likely to want COVID-19 testing, based on the sampling method and scenario proposed.

When the sampling method proposed was a nasopharyngeal swab, participants were more likely to accept testing in the return to school scenario (100% [95%CI: 95, 100]) than the positive contact scenario (79% [95%CI: 66, 88]; mean difference 21% [95%CI: 9, 34]). No significant difference was found between the fever scenario and the other two scenarios for the nasopharyngeal swabs. Participants were equally likely to accept SB sampling for all three scenarios (98% [95%CI: 89, 99] for the return to school scenario; 98% [95%CI: 89, 99] for the fever scenario; 92% [95%CI: 82, 97] for the positive contact scenario).

Fifty-eight percent of children rated their pain to be significant (4/10 or higher) on the FPS-R during the nasopharyngeal swab, whereas no participant described significant pain during saliva sampling (Fig 2). Ninety-six percent of children reported 0/10 pain with saliva sampling. Ninety percent of children would prefer to have saliva sampling in the future if they had to be tested again (Fig 3). The two participants who preferred the nasopharyngeal swab stated that it was quicker than the saliva test (expectoration) or that the process of expectorating 1ml of saliva was tedious. All participants (N = 8) who underwent a sponge technique for their saliva collection preferred the saliva test to the nasopharyngeal swab. 66% of primary decision makers indicated they would prefer their child undergo a nasopharyngeal swab if it were true that SB sampling was 10% less sensitive. In this scenario, primary decision makers preferred a nasopharyngeal swab less frequently in younger children (< 12 years) compared to older children (> 12 years) (55% vs 88% respectively). Across all scenarios, the likelihood of accepting a saliva test did not appear to be influenced by the type of saliva testing method used (sponge vs. expectoration).

Fig 2

Self-reported pain after NP swab using revised Face Pain Scale (FPS-R, percent of participants).

Fig 3

Preferred test in case of future need for testing (percent of participants).

55% of primary decision makers indicated they would want their child to receive a nasal numbing spray prior to their nasopharyngeal swab even if it meant waiting 10 minutes for the spray to have an effect.

Discussion

Primary decision makers of pediatric patients 6 years and older who have just experienced a SARS-CoV-2 test are likely to accept testing again, regardless of whether it is a nasopharyngeal swab or saliva sample. Unlike saliva sampling, however, the acceptably of nasopharyngeal swabs was different when the indication for testing changed. Primary decision makers were less accepting of future nasopharyngeal swabs when their child was an asymptomatic contact of a COVID-positive case, compared to when it was a requirement for returning to school. The acceptability of the saliva sample, in contrast, remained high across all scenarios. One of the two participants who preferred a nasopharyngeal swab commented that producing 1ml of saliva was a slow and unpleasant process. It should be noted that most saliva-based assays require only 0.05 to 0.3ml for testing [5]. Alternatively, the sponge collection process appeared to have been well tolerated. After experiencing both tests, the vast majority of children indicated a preference for saliva sampling, which was rated, almost unanimously, as painless. Despite this finding, most primary decision makers indicated they would choose nasopharyngeal swabs over saliva samples if it were true that saliva samples were 10% less sensitive.

Nasopharyngeal swabs do not appear to be unpleasant enough to influence caregiver decisions on future testing. This is similar to the result found by Moisset et al. [12], who reported 89% of young adult volunteers in their study rated the acceptability of the nasopharyngeal swab as being 8/10 or higher and 100% would accept the same technique again if indicated. Twenty-eight percent of participants in that study rated pain as being significant (4/10 or higher), which is half the proportion of participants who reported significant pain with nasopharyngeal swabbing in our results. Their trial did not include children, or investigate primary decision maker’s willingness to accept a sampling method on behalf of their children.

Primary decision makers in our investigation may have been less accepting of a nasopharyngeal swab in the context of asymptomatic contact with a positive COVID-19 case because the consequence of not testing is less obvious or impactful, compared to the scenario where their child cannot return to school without a test. Given that saliva sampling was highly accepted in all the proposed scenarios, it may be that primary decision makers are more likely to accept this modality over a nasopharyngeal swab when testing is perceived as less valuable (e.g., voluntary asymptomatic screening, mild or atypical COVID-19 symptoms). Other studies have shown that COVID-19 test acceptability can vary based on factors of convenience or comfort, such as turnaround time for results [13] or the ability to self-test at home [1]. Further study and delineation of this variability will help determine which sampling options, in which clinical scenarios, most effectively balance test reliability with caregiver willingness to have children tested.

In our study we asked participants if they would accept a 10% reduction in sensitivity using saliva sampling instead of nasopharyngeal swabbing, to determine whether primary decision makers would be willing to trade a reduction in test accuracy for sampling comfort. The actual difference in sensitivity between saliva sampling and nasopharyngeal swabs is not definitively known at present, and likely varies in different clinical scenarios. While initial meta-analyses have estimated sensitivity of saliva samples to be similar to nasopharyngeal swabs [3, 4], Mestdagh et al. [14] found that sensitivity varied widely according to saliva collection technique and viral load. Tan et al. [15] also found that test performance varied significantly according to saliva collection and processing technique, and suggested in their review that saliva assays may perform better than nasopharyngeal swabs in optimal conditions.

Determining the ideal test to either screen for, or diagnose, COVID-19 is an on-going area of research that must take into account the circumstances and goals of testing. With the onset of the Omicron variant, which seems to be more transmissible but potentially less severe than previous SARS-CoV-2 variants, testing policies continue to adapt. This will also be true if future variants arise with different clinical characteristics [16]. Test accuracy, cost, feasibility and acceptance are all important factors which must be understood to pivot into effective testing strategies. Our study contributes insight into test acceptability for the pediatric population after children have experienced different sampling methods in a community setting. The implication that acceptability varies by testing rationale more readily when the sampling method is uncomfortable will remain relevant over the evolving course of the pandemic, particularly as the utility and perceived value of testing changes over time. Future studies should further elucidate how different populations respond to the experience of COVID-19 testing in other settings, such as the in-patient setting or when patients are highly symptomatic.

In addition to saliva collection and nasopharyngeal swabs, other alternatives examined in the literature include anterior nasal swabs, throat swabs and combinations of both. It is likely that similar factors identified in this research influence the acceptability of other testing modalities. Additional research is required to further define the acceptability of emerging SARS-CoV-2 testing techniques [5].

Limitations

There are several limitations to this study. First, as no validated survey to assess SARS-CoV-2 test acceptability exists in the literature, we had to develop a survey to assess our primary outcome, based on best practices [8]. Second, this sample consists of those who went to assessment centers for testing and then consented to be included in a research study, which may affect generalizability. However, the benefit of obtaining the opinions of youth and families who experienced testing with both modalities is valuable regardless of selection bias. The education level of the recruited families was higher than what might be expected of the general population and could have an impact on the generalizability of the results. This is possibly due to the urban location of the testing center.

Conclusion

Though most youth find saliva sampling painless and prefer it to nasopharyngeal swabs, primary decision makers present for the experience generally remain accepting of both methods for COVID-19 testing. Acceptance of nasopharyngeal swabs, however, varied based on testing rationale. SARS-CoV-2 testing strategies should bear in mind that primary decision makers seem more accepting of uncomfortable sampling techniques when they see benefit to testing, and perceptions of test accuracy can supersede the desire for more comfortable sampling. Patient and family preferences should be considered by public health policy makers, especially when testing modalities are comparable. Further study of SARS-CoV-2 sampling accuracy and acceptability will help determine the ideal application for each modality.

STROBE statement—Checklist of items that should be included in reports of cross-sectional studies.

(DOCX)

Click here for additional data file.

Supporting information–Survey.

(DOCX)

Click here for additional data file.

8 Apr 2022

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Reviewer #1: The authors present a very relevant study, one which can be informative for future diagnostic practices. We have seen first-hand through the pandemic how testing aversion can lead to delayed testing and testing avoidance, both which can have serious consequences for public health. We must learn from our experiences through the pandemic and continue to innovate the rest of our clinical diagnostics to improve acceptability to the patient to encourage greater adherence to testing - and less fear of clinical space. While a few questionnaires have been issued to evaluate people's thoughts and experiences with sampling technique, this is the first that I am aware of to also study the physical response to these samples. Thus, I commend the authors on their study and bringing this issue to light.

Major comments:

Lines 74-76: There was a recent study evaluating test acceptability in schools which may require this text to be updated a little: https://journals.sagepub.com/doi/full/10.1177/00333549221074395. The authors might like to review this recent publication in case any of the references need to be updated or if this paper adds any additional support to their work: https://www.dovepress.com/acceptability-of-community-saliva-testing-in-controlling-the-covid-19--peer-reviewed-fulltext-article-PPA

Methods: the sampling procedure for both NP and saliva sampling is missing. This is important to the study for the reader to understand especially, which saliva sampling technique they received and how they found this. It would also be helpful to attach the saliva sampling SOP/IFU into the appendix so people can evaluate this - ie, were people coaxed? This can help with collection. The authors could also discuss that 1 mL is a relatively large amount to collect considering many major saliva tests only require 50-300 ul of sample, meaning that less could be collected, further improving acceptability.

Conclusion: why is there a sudden mention of Mers?

Minor comments:

As 'NP' and 'nasopharyngeal' contribute the same word count and as 'saliva-based' and 'SB' also contribute the same word count (or in many places could simply be 'saliva'), I recommend that 'saliva' and 'nasopharyngeal' be written in full. As this work will have broad appeal, this will be easier for the less-experienced reader to follow along with.

Update 'SARs-CoV-2' to 'SARS-CoV-2' throughout.

Line 225: This makes a good reference for how it is the robustness of saliva testing (and sample collection) that can affect sensitivity (rather than straight 'saliva' itself) - this is important as with robust methods, saliva performs equal to or better than swabs: https://www.thelancet.com/journals/lanres/article/PIIS2213-2600%2821%2900178-8/fulltext

Reviewer #2: Major Comments

- Why were there two different saliva sampling methods used in the study? As this is evaluating preference the NP stays constant, but a sponge collection and spit would add additional variables to the already limited number of patients. Ideally additional participants would be added to remove the sponge method. If not possible, the data should be separated between method types.

- I would suggest adding more details about the questions used in the survey. At the moment the material and methods of what was asked was unclear and requires going to supplemental data to review the survey to understand what was asked.

Minor Comments

Ln 257 and 261: This seems to be a typo as its stated as Mers and not SARS.

One complaint and issue with saliva testing is obtaining enough volume to perform all testing. Was there any issues to obtain the 1mL from subjects?

I would add in the limitations that the majority of primary decision makers had some college education or higher, which may have skewed results, especially when asking about sensitivity.

Reviewer #3: This was a very nice study looking at the acceptability of saliva and NP swab for testing children for COVID-19. This is particularly interesting because almost all other studies have focused solely on measures of test sensitivity and accuracy as opposed to patient comfort and ease. While NP swabs are the gold-standard, they are onerous to perform and so it is good to know when the slight increase in sensitivity for the test might outweigh concerns about the patient anxiety and comfort, particularly children. I thought the paper was quite good overall and suggest just some additional discussion/background to help readers place the results in context of other studies on COVID-19 testing:

1. I think it might be helpful to include some discussion of limitations of both techniques in general. For instance some patients cannot do a saliva test because they cannot self collect a sample (e.g., very young infants, patients with certain disabilities). Some patients are very difficult to get NP swabs on because of nasal anatomical/pathological issues. There's also typically a difference in overall cost of the tests with saliva typically being a bit cheaper overall since saliva tests do not require specialized swabs/supplies or highly trained medical staff to collect.

2. The authors also do not discuss other less invasive swabs (anterior nasal, oral, etc). There have been some studies using these in other settings where NP swabs are not easy to administer.

3. One of the more interesting findings is that parents would still be ok using saliva over NP swabs even if the NP swab was 10% more accurate. This might be a good place to discuss the relative accuracy of these two testing modalities.

4. This was done on a population of patients that had symptoms or known exposures to SARS-CoV-2 and thus, one would assume that they would be more likely to want better diagnostics than they would if this test was for a screening application. It may be useful to have a follow up survey of healthcare professionals or reference some work in the literature that surveys clinicians to compare the acceptability of saliva over NP swabbing in different applications. I would assume that clinicians would in general prefer NP swabbing for diagnostics as it is the gold standard but the data on pain and patient acceptability may sway their decision based on the reason for the COVID-19 test.

Overall, this was a well designed study, which fills a clear gap in our understanding of the COVID-19 testing landscape.

Reviewer #4: This is a very relevant, well-conceived and well-written study of patient preferences in the context of a rapid increase in the experience of upper respiratory sampling in all age groups. I listened to my asymptomatic niece scream during a required NP swab for a dental appointment, with an absolutely massive swab, and wondered why we couldn’t have SB screening for kids like in BC?? How individuals weigh the risks and benefits in the context of sampling quality is a fascinating element of this study – that more pain is acceptable with more gain, and whether the case is symptomatic, asymptomatic, and/or required to test might all influence which test is preferable. I am very intrigued by the older kids who preferred NP, such an interesting perspective.

Your opening statement in the introduction seems no longer quite accurate post-Omicron. Not suggesting any specific changes, but it would be nice to see some additional perspectives in Intro/Discussion on how your findings might be different now, when the “scenario” is declining availability of free, trackable testing and rampant pauci-symptomatic infections at school?

How did you put the survey on the electronic device and link to RedCap, in detail? Software? Scripts? Device used? This is just for my information because I want to do this next month!

I am curious about differences in swabs used for children (thickness, fluffiness vs. sharpness of swab head) and how painful each type might be, for example, if an “adult-sized” swab was used on a little one – could this account for some of the difference between yours and Moisset’s study?

Figure 1: Add y axis title (“% of participants”), remove “%” from tick labels, y axis should end at 100, not go past it. In legend, “Saliva test” should be “Saliva-based test” or just use “SB” and “NP” to be consistent with text. Figure Caption: “at least likely” is ambiguous, do you mean just the top two Likert points? Always use curly quotation marks.

Figure 2: Add y axis title (“% of participants”), remove “%” from tick labels, only label every second tick (at 10% rather than 5% intervals). Figure caption is unclear, how about: “Self-reported pain after NP swab using revised Face Pain Scale (FPS-Re, percent of participants).”

Figure 3: In legend, “Saliva test” should be “Saliva-based test” to be consistent with text. Figure caption is unclear, how about: “Preferred test in case of future need for testing (percent of participants).”

Is “Interpretation-Limitations-Conclusion” a suggested PLoS One structure? Just “Discussion” (no sub-heads) seems preferable.

This paper is low on refs. It is a unique study, so this makes sense, however some additional context about saliva testing for COVID and other infections, and pediatric screening vs. diagnostics in general, would be much appreciated.

Supporting Information/"Appendix": Not sure if I see the utility of attaching these. STROBE is not referenced anywhere else that I noticed, so what is it supporting? The survey “appendix” seems a bit repetitive to the main text and is only referenced once (reference should be to SI, not Appendices).

Minor comments and style suggestions (please take or leave):

Throughout – Ref numbers and Figure refs on the wrong side of the punctuation or with missing spaces between ref and text.

Title - Line 1: typo in SARS-CoV-2

Line 46: “prior” instead of “a priori”

Line 62: “factors that influence sampling” instead of “factors sampling”

Line 66 and 68: parentheses instead of square brackets

Line 70: hyphen in “under-represented”

Line 72: delete “It has been shown that”

Line 95: “decision” instead of “decisions” – Just curious, when is assent appropriate?

Line 110: Adolescents – what is exact age group?

Line 113: “our own” instead of “a de novo”

Line 118: italicize e.g.

Line 119: Too much punctuation - “likely, see Appendix)” instead of “likely; (see Appendix))

Line 120: Square brackets look weird to me in paragraph text.

Line 121: “by asking yes or no” instead of “with direct binary”, “concluding” instead of “final”

Line 129-31: A bit wordy… “were dichotomized to likely and not likely (including neutral).”

Line 142: Wordy… “Convenience sample size was 50 participants”.

Table 1 – Needs cleaning up, too many ugly square brackets! Spaces after commas. No need for “+” or “[%]” or “, yes” – Remove extra space before “CEGEP”.

Line 174 and 176: Space before “ 2”. Space before “ 3”.

Line 182: Period after “vs.”

Line 182-4: Sounds like the parent wants the numbing spray for themselves – “prefer a nasal numbing spray be offered to their child” ?

Line 193: “acceptability” instead of “acceptably”

Line 195: “contact of” instead of “contact with”, comma after “case,”

Line 203: “et al.” instead of “et. al.”

Line 212: “not testing is less obvious” instead of “not testing is not as obvious”

Line 215: “testing is perceived as less valuable” instead of “the value of testing is not seen as high”, italicize e.g.

Line 219: “most effectively” instead of “best”

Line 225: “likely varies in different” instead of “is likely different in different”

Line 226-7: italicize “et al.”

Line 227: “that sensitivity” instead of “that te sensitivity”

Line 229: “ranged from 22-94%” instead of “to be as low as 21.9% and as high as 93.9%”

Line 229-30: “comparator” instead of “gold standard”

Line 231: no hyphen in “ongoing”

Line 238: no hyphen in “inpatient”

Line 239: “understanding feasibility and acceptability of saliva-based screening” instead of “understanding acceptance”

Line 241: “since” instead of “as”

Line 242-3: “designed a survey to assess our primary outcome, based on best practices (6).”

Line 247: Briefly explain what is a “collider”?

Line 248: “youth and their families” instead of just “youth”, “is valuable regardless” instead of “justifies the risk”

Line 249-51: Axe the last two sentences of this paragraph.

Line 256: “varied” instead of “is more prone to vary”

Line 257: “SARS” instead of “Mers”

Line 259: “supercede” is mis-spelled

Line 261: “comparable” instead of “non-inferior or equivalent”, “SARS” instead of “Mers”

Line 262: “ideal application for each modality” instead of “ideal use for the differing modalities”.

Line 269-74: Add cédille to “François”

**********

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: No

Reviewer #3: No

Reviewer #4: Yes: John J. Schellenberg

[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.

2 Jun 2022

Dear reviewers,

We are truly thankful for your time and efforts invested in reviewing our manuscript. Your insightful comments helped us improve the paper significantly.

We have addressed comments and suggestions on a point-by-point basis in the "Reviewers response" document. We invite you to review this document as well as the new version of the manuscript.

We are hopeful that you will find our modifications to your satisfaction and welcome questions, comments and suggestions.

Sincerely,

Francois Gagnon, MD, FRCPC

Pediatric Emergency Medicine Fellow

Children's Hospital of Eastern Ontario

Submitted filename: Reviewers Response.docx

Click here for additional data file.

21 Jun 2022

Nasopharyngeal Swabs vs. Saliva Sampling for SARS-CoV-2 Detection: A Cross-Sectional Survey of Acceptability for Caregivers and Children after Experiencing Both Methods

PONE-D-22-07725R1

Dear Dr. Gagnon,

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,

A. M. Abd El-Aty

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Please add the product name/supplier details of sponge-based saliva kit in the galley proof, as requested by reviewer # 1

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: (No Response)

Reviewer #2: All comments have been addressed

Reviewer #3: 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

Reviewer #3: Yes

**********

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

Reviewer #1: I Don't Know

Reviewer #2: Yes

Reviewer #3: 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

Reviewer #3: (No Response)

**********

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

Reviewer #3: 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: The authors have submitted a robust revision of their work. The only minor comment I have is that the sponge-based saliva kit used needs to have product name/supplier details.

Reviewer #2: The authors addressed all of my comments that I presented on the first review. No further changes are needed after the revisions.

Reviewer #3: The authors have addressed all my prior concerns. The paper is well written, and relevant to the current ongoing pandemic situation.

**********

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

Reviewer #3: No

**********

30 Jun 2022

PONE-D-22-07725R1

Nasopharyngeal Swabs vs. Saliva Sampling for SARS-CoV-2 Detection: A Cross-Sectional Survey of Acceptability for Caregivers and Children after Experiencing Both Methods

Dear Dr. Gagnon:

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. A. M. Abd El-Aty

Academic Editor

PLOS ONE