Effects of COVID-19 pandemic–associated reduction in respiratory infections on infantile asthma development

Abstract

BackgroundIt is speculated that the COVID-19 pandemic associated reduction in the prevalence of respiratory tract infections has influenced on the incidence of asthma in infants. ObjectivesWe investigated an association between the reduction in viral infections and the reduction in asthma in infants. MethodsThe subjects were infants born in the early stages of the COVID-19 pandemic in Japan, which began in February 2020. A questionnaire survey related to asthma and allergy was conducted at 18 months and 3 years old. These results were compared to those of age-matched infants during the non-pandemic period. ResultsThere were no epidemics of viral infectious diseases until the target child was 18 months old. At 18 months, the incidence of asthma/asthmatic bronchitis diagnosed by physicians in pandemic infants was significantly lower than that in non-pandemic infants. In 3-year-old infants, no marked difference was observed between non-pandemic infants and pandemic infants, except for an increase in RSV infection in pandemic infants. In a comparative study of the same infants at 18 months and 3 years old, an increased prevalence of asthma/asthmatic bronchitis was observed in pandemic infants. Furthermore, the incidence of asthma after RSV infection in pandemic infants was significantly lower than that in non-pandemic infants. ConclusionThe COVID-19 pandemic-associated reduction in respiratory tract infections may have reduced the incidence of asthma in infancy, and RSV infection after 18 months old had little effect on the onset of asthma. These results indicate the importance of preventing respiratory tract infections in early infancy.