Detection of human respiratory viruses among hospitalized children aged ≤ 5 years in Wuhan (China), from January to May 2020.

Dear editor,

Respiratory virus infections can lead to influenza-like illnesses (ILIs), which may cause acute respiratory tract infections, and are a significant source of morbidity and mortality worldwide. , These kinds of infections occur mainly in infants and children, who can experience up to five or six episodes in any given year. In December 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections were reported in Wuhan, which caused coronavirus disease 2019 (COVID-19). This novel coronavirus has spread across the world leading to a new global pandemic. The spread of SARS-CoV-2 has been curtailed by the implementation of various public health interventions, including lockdowns in Wuhan City, from January 23, 2020 to April 8, 2020. In this Journal, Mensah et al. reported that national lockdowns were associated with large declines in SARS-CoV-2 infection rates. However, the impact of various public health interventions on the transmission of other respiratory viruses remains largely unknown. In this study, we present our findings from Wuhan during this same lockdown period.

Our study identified 1404 inpatient cases from Hubei Maternal and Child Health Hospital, who underwent testing for respiratory pathogens between January and May 2020. The samples were taken from infants and children aged ≤ 5 years, among whom 568 of them were female (40.46%) and 836 were male (59.54%). The mean age (± SD) of the patients was 1.21 ± 1.36 years (median: 0.83 years; interquartile range (IQR) 0.08–2.00 years) (Supplementary Table 1). We also tested for eight different respiratory viruses, including adenovirus (ADV), influenza A virus (Flu A), influenza B virus (Flu B), parainfluenza virus (PIV) 1–3, respiratory syncytial virus (RSV), and SARS-CoV-2. Analysis of the samples for each of these respiratory viruses, except for SARS-CoV-2, was performed using a rapid antigen detection kit (DIAGNOSTIC HYBRIDS, INC.). Detection of SARS-CoV-2 was performed using real-time RT-PCR detection of the N and RdRp genes, and positive samples were verified using an official approved clinical diagnostic kit (DAAN Gene Co., Ltd) as previously described.

Of the 1404 hospitalized pediatric patients, 407 (407/1404, 28.99%) were positive for at least one pathogen, including 390 single infections and 17 co-infections (Supplementary Table 1). Among the single infections, RSV (292/1404, 20.80%) was the most common, followed by Flu A (51/1404, 3.63%), Flu B (21/1404, 1.50%), ADV (14/1404, 1.00%), PIV2 (4/1404, 0.28%), PIV1 (3/1404, 0.21%), SARS-CoV-2 (3/1404, 0.21%), and PIV3 (2/1404, 0.14%) (Supplementary Table 1). RSV was the predominant pathogen in all age groups (Supplementary Table 1). We also noted that the number of inpatients peaked in January and then decreased drastically in the following months, shifting from 813 cases in January to 60 cases in May 2020 (Fig. 1 ). The monthly detection rates for these respiratory viruses ranged from 0 to 46.37% for the patients tested, and the peak detection rate was observed in January 2020 (377/813, 46.37%). The detection rate then decreased dramatically from 19.69% (25/127) in February 2020 to 0% (0/60) in May 2020 (Fig. 1). In addition, the number of different types of viruses detected decreased significantly, from eight in January, to four in February, to none in May 2020 (Supplementary Table 2). Most of the inpatients with a single respiratory infection were diagnosed with lower respiratory tract infections (339/390, 86.92%), and RSV accounted for these infections (272/339, 80.24%) (Supplementary Table 3, Supplementary Fig. 1).

Fig. 1

Monthly distribution of respiratory virus positive subjects (light orange bars), negative subjects (orange bars) and positive rate (gray line) in Wuhan, from January to May 2020.

Among the 1404 enrolled patients, seven (7/1404, 0.50%) tested positive for SARS-CoV-2, including three single infections and four co-infections. All seven patients were hospitalized before January 23, 2020, the day when the lockdown started (Supplementary Table 4). During the lockdown, the COVID-19 patients were centralized quarantined, and no more SARS-CoV-2 positive patients were hospitalized in the hospital over the course of this study. These seven patients were infants aged ≤ 2 years with two patients being ≤ 1 month old (Supplementary Table 4). All seven patients were diagnosed with respiratory tract infections, and five experienced high fever (> 38.5 °C). All of these patients (except for patient 5 who was transferred) were treated with antibiotics and/or antivirals and recovered within 10 days.

This study describes the epidemiology of the respiratory virus infections of inpatients aged ≤ 5 years in Wuhan City during the Wuhan lockdown in 2020. We found that both the number of inpatients and the detection rates of respiratory viral infections decreased dramatically after COVID-19 lockdown measures were implemented. Our findings are consistent with those of other studies on the circulation of respiratory viruses during the COVID-19 pandemic. , These results strongly suggest that nonpharmaceutical interventions, including lockdowns, interrupt or reduce the spread of respiratory viruses. Our results also revealed that all seven SARS-Cov-2 positive infants contracted the virus before lockdown started. Additionally, in the early months of the pandemic, when the testing capacity was insufficient, SARS-CoV-2 infections in young children may have contributed to the spread of the virus. As reported in other similar cases, all six infants recovered within 10 days of hospitalization, suggesting that the clinical manifestations of COVID-19 in children may be less severe than that of adult patients. , The findings of this study were subject to at least three limitations. First, only a single center was enrolled in the study. Second, patients preferred to treat themselves at home during the lockdown period, reducing the number of patients seeking professional treatment, which may also have led to a reduction in inpatient admissions. Third, other common respiratory viruses, including rhinoviruses and common human coronaviruses, were not evaluated or enrolled in this study. Nevertheless, our results highlight the impact of nonpharmaceutical interventions, including lockdowns, on the spread of respiratory viruses.

Declaration of Competing Interest

None.