Decrease in pediatric inpatients with respiratory syncytial virus infection during severe acute respiratory syndrome coronavirus 2 pandemic – Kang – – Pediatrics International

Since the onset of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, strict measures have been recommended in Japan to prevent disease transmission, such as wearing masks in public, practicing hand hygiene, encouraging from social distancing, remote working, cancellation of major events and school closures. These measures have not only affected the transmission of SARS-CoV-2, but have also prevented the transmission of other respiratory viruses such as seasonal flu.1 Respiratory syncytial virus (RSV) is a highly contagious respiratory pathogen that causes bronchiolitis and pneumonia.2 There is there is no vaccine for RSV, so the standard precaution is to interrupt its transmission.3 However, it is difficult for children under school age to practice effective hand hygiene practices, wear masks and maintain social distancing.

To investigate the effectiveness of infection prevention measures for young children, we compared the weekly number of pediatric patients with RSV infections in 2020 with those in the previous two years (2018-2019) in Saitama Prefecture, Japan. Saitama Prefecture, which borders Tokyo, has 7.3 million inhabitants, of which 0.9 million are children (<15 years).

We used data from 2018 to 2020 from the Japanese Pediatric Society Saitama Branch RSV Infection Surveillance Working Group. This group collects weekly data on the number and age of hospitalized patients with RSV infections, as diagnosed by physicians based on clinical signs or laboratory findings from 22 hospitals that have treated almost all pediatric patients in Saitama Prefecture since 2018. The numbers of intubated patients were also collected.

Continuous variables, such as the annual mean of the weekly rates (the number of patients admitted divided by the number of hospitals) were compared using analysis of variance; categorical variables, such as ratios, were compared using the 2 test with the Fisher modification, if applicable. Statistical significance was defined as P < 0.05. Analyzes were performed using R software, version 4.0.3 (R Foundation for Statistical Computing, Vienna, Austria). The study has been approved by the Institutional Ethics Committee (No. 2020-05-008).

There were 1,515, 1,465 and 161 patients with RSV infections in 2018, 2019 and 2020, respectively (Fig. S1). The median age was 0 years for the three years. In 2018 and 2019, the prevalence of RSV infections increased in the autumn. While RSV infections peaked between weeks 30 and 40 in 2018 and 2019, there was no peak in 2020 (Fig. 1). The mean number of weekly infections per hospital differed significantly over the years (P < 0.05). Of the admitted patients with RSV, 2.2% (33/1,515) were intubated in 2018, 2.6% (38/1,465) in 2019 and 2.5% (4/161) in 2020; there was no statistically significant difference in the ratios between the groups (P = 0.77).

Average number of pediatric patients with respiratory syncytial virus (RSV) infections admitted weekly per hospital in 2018-2020, and events related to the SARS-CoV-2 pandemic in 2020. (), 2018; (), 2019; (), 2020.

The number of pediatric patients with RSV infections was significantly lower in 2020 than in previous years in Saitama, Japan. It is well known that RSV first presents as a common cold in family members and is transmitted to infants.2 This study suggests that preventive measures against respiratory infections taken by the general population may also reduce the incidence of infections in infants without being influenced by meteorological conditions. There was no significant difference in the rate of endotracheal intubation in patients; therefore, the RSV itself was unlikely to become less virulent. Even after the reopening of the schools, the number of admitted patients with RSV infections remained low. School closures would therefore probably not have a critical impact on the RSV epidemic.

In Japan, the National Institute of Infectious Diseases (NIID) collected the number of RSV patients as a pediatric sentry watch. According to the NIID weekly reports, the average number of weekly infections per sentinel station has decreased significantly in 2020 (Fig. S2). However, during the pandemic in Italy, there was a significant decline in access to pediatric care, reflecting the reluctance of parents and caregivers to risk exposure to SARS-CoV-2 in hospitals.4 By focusing on inpatients with moderate to severe RSV infections could therefore be the bias caused by the reluctance of health care providers to visit hospitals because of the SARS-CoV-2 pandemic.

Interestingly, in Australia, the number of RSV cases increased in October; however, the reason is unclear.5 Close monitoring is necessary to determine the factors that could lead to an increase in the number of patients with RSV infections after the low prevalence of RSV infection in 2020. It is vital to adopt sustainable precautions continue to take, such as hand hygiene and wearing masks, to reduce the transmission of respiratory infections.


We would like to thank the Japanese Pediatric Society Saitama Branch RSV Infection Surveillance Working Group for data collection The following members are: Yutaka Kawano, MD, PhD, Saitama Children’s Medical Center, Shoichi Oyama, MD, Saiseikai Kawaguchi General Hospital, Tetsuya Kunikata, MD , PhD, Saitama Medical University Hospital, Toshihiro Kobayashi, MD, PhD, Kobayashi Clinic, Seiji Sato, MD, PhD, Saitama City Hospital, Hisanori Sobajima, MD, PhD, Saitama Medical University Saitama Medical Center, Shigeharu Hosono, MD, PhD, Jichi Medical University Saitama Medical Center, Mahito Mine, MD, Mine Pediatrics and Ko Ichihashi, MD, PhD, Jichi Medical University Saitama Medical Center.


We have not received any fee grant or other form of payment to produce this manuscript.


The authors declare no conflict of interest.

Contributions from authors

KY and OT conceptualized and designed the study, drafted the first manuscript, and reviewed and revised the manuscript. KY and KT designed the data collection tools, collected data, performed initial analyses, and reviewed and revised the manuscript. IK coordinated and supervised the data collection and critically assessed the manuscript for important intellectual content. All authors approved the final manuscript as submitted and agree to be responsible for all aspects of the work.

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