Impact of COVID-19 on Respiratory Virus Infections in Children, Japan, 2018-2023

Abstract

Background: COVID-19, caused by SARS-CoV-2, was first documented in Japan in January 2020. We previously reported an increased risk of rhinovirus infections among children during the early phase of the COVID-19 pandemic. Here, we assessed the impact of COVID-19 on respiratory virus infections after SARS-CoV-2 spread nationwide.

Methods: We analyzed clinical specimens from 4012 patients with respiratory infections in Yokohama, Japan from January 2018 to April 2023.

Results: Among 15 representative respiratory viruses we detected (influenza virus, rhinovirus, coxsackievirus, echovirus, enterovirus, human coronavirus 229E, HKU1, NL63, and OC43, human metapneumovirus, human parainfluenza virus, human parechovirus, RSV, human adenovirus, human bocavirus, human parvovirus B19, herpes simplex virus type 1, and varicella-zoster virus), influenza was most affected by the COVID-19 pandemic, with no influenza viruses detected for nearly 3 years.

Conclusions: The decrease in influenza infections following the emergence of SARS-CoV-2 may have contributed to the previously reported increase in rhinovirus infections. The rhinovirus outbreak, rather than SARS-CoV-2, may have contributed to the decrease in enveloped virus infections (RSV, parainfluenza viruses, metapneumovirus, and coronavirus 229E, HKU1, NL63, and OC43), possibly due to negative virus-virus interactions.

Keywords: COVID‐19; SARS‐CoV‐2; influenza; respiratory syncytial virus; rhinovirus; viral interference.

Figure 1

The number of COVID‐19 patients reported and the number of respiratory viruses detected by age group from January 2018 to April 2023 in Yokohama, Japan. All patients (A; n = 4012), children younger than 10 years (B; n = 2177), patients aged 10–59 years (C; n = 1313), and patients aged 60 years or older (D; n = 500). Representative respiratory viruses with maximum monthly values of 5 or more are shown. Parentheses next to the virus name indicate the total number of viruses detected. The gray line indicates the number of COVID‐19 patients reported by the local government. Age information was not available for 22 of 4012 patients.

Figure 1

The number of COVID‐19 patients reported and the number of respiratory viruses detected by age group from January 2018 to April 2023 in Yokohama, Japan. All patients (A; n = 4012), children younger than 10 years (B; n = 2177), patients aged 10–59 years (C; n = 1313), and patients aged 60 years or older (D; n = 500). Representative respiratory viruses with maximum monthly values of 5 or more are shown. Parentheses next to the virus name indicate the total number of viruses detected. The gray line indicates the number of COVID‐19 patients reported by the local government. Age information was not available for 22 of 4012 patients.

Figure 2

The number of COVID‐19 patients reported and the detection rate of respiratory viruses in children younger than 10 years from January 2018 to April 2023 in Yokohama, Japan. The detection rate for each virus was calculated as the number of detections per analyses per month. Representative respiratory viruses with a maximum monthly detection rate of 10% or more are shown. The gray line indicates the number of COVID‐19 patients reported by the local government.

Figure 3

The number of COVID‐19 patients reported and the genotypes of influenza virus, rhinovirus, and respiratory syncytial virus detected in children younger than 10 years from January 2018 to April 2023 in Yokohama, Japan. The number of viruses of each genotype is shown. Parentheses next to the virus name indicate the total number of viruses detected. The gray line indicates the number of COVID‐19 patients reported by the local government.