New diagnoses of childhood asthma declined by half in the first year of the COVID-19 pandemic, which may be due to pandemic-related changes in infections and other factors that may have altered the incidence of childhood asthma, according to a new study.

“Given the similar findings from Japan and the United States, these results suggest that the pandemic caused many fewer children to develop asthma in various places around the world, at least early on,” Daniel Horton, MD, MSCE, a core faculty member at the Center for Pharmacoepidemiology and Treatment Science at Rutgers Institute for Health, Health Care Policy and Aging Research (IFH), and the lead author of the study, said in a statement.1

The results of this population-based retrospective cohort study were published in Respiratory Research.2

About 4.8 million children have asthma in the United States, with symptoms including difficulty breathing, wheeze, cough, and tightness or pain in the chest, according to data from the National Center for Health Statistics. Although prior studies have shown declines in the worsening of childhood asthma during the pandemic, little was known about the rate of new asthma diagnoses during the pandemic.

This study is a follow-up from a Japanese study3 that aimed to identify rates of diagnosis in the United States. That study identified a pronounced decline in new asthma diagnoses. The monthly number of patients with newly diagnosed asthma was decreased by 59%, and while there was a slight trend upward toward the tailend of the study, new diagnoses remained lower than they would have been without the pandemic.

The new study used data from the Health Core Integrated Research Database, allowing the researchers to identify patients less than 28 years with no prior diagnosis of asthma and compare rates of new diagnoses from 2020 with rates during the previous 3 years.

Compared with rates from the 3 previous years, the crude incident diagnosis rates for asthma declined by 52% across the first year of the pandemic, with adjusted odds ratio (0.47; 95% CI, 0.43-0.51).

The researchers of this study believe that decline in childhood asthma may be due to fewer incidences of rhinoviruses, otherwise known as common colds.

“We think this may have occurred in part because, earlier in the pandemic, children were separated, wearing masks and getting fewer regular colds that could trigger asthma,” said Horton, who is also an assistant professor of pediatrics at Rutgers Robert Wood Johnson Medical School and an assistant professor of epidemiology at Rutgers School of Public Health. “No one wants to keep children out of school or separated, but having kids wear masks while they have a cold or the flu might be a way to keep other kids who are at risk for developing asthma a little safer.”

The researchers also acknowledged some limitations to their study, which included the possible misclassification of asthma diagnosis due to their diagnostic algorithm. However, the researchers backed their algorithm on previously validated and highly accurate algorithms from other studies.

Overall, the researchers believe these findings add to the importance of understanding why childhood asthma diagnoses significantly declined during the first year of the pandemic, and if masking and social distancing may be the cause.


1. RutgersU. Childhood asthma declines during COVID-19 pandemic. EurekAlert! Published March 31, 2023. Accessed April 5, 2023.

2. Horton DB, Neikirk AL, Yang Y, et al. Childhood asthma diagnoses declined during the covid-19 pandemic in the United States. Respiratory Research. 2023;24(1). doi:10.1186/s12931-023-02377-7

3. Matsumoto N, Kadowaki T, Takanaga S, Ikeda M, Yorifuji T. Impact of COVID-19 pandemic-associated reduction in respiratory viral infections on childhood asthma onset in Japan. J Allergy Clin Immunol Pract. 2022;10(12):3306-3308.e2. doi:10.1016/j.jaip.2022.09.024

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