COVID-19 lockdown reduced childhood wheezing and bronchiolitis cases

In a recent research letter published in the journal JAMA Network Open, scientists in Italy compared the rates of respiratory medication usage and wheezing due to bronchiolitis among children born during the coronavirus disease 2019 (COVID-19) pandemic-associated lockdowns in Italy and those born in the winter months before the pandemic, when the incidence of respiratory syncytial virus infections was high.

Research letter: Wheeze Among Children Born During COVID-19 Lockdown. Image Credit: Herlanzer / Shutterstock

Background

Emerging evidence from epidemiological studies shows that the lockdowns and social distancing measures implemented in many countries to curb the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) also reduced the incidence rates of other respiratory viruses. Other disease mitigation measures, such as frequent handwashing and masking, have also contributed to lowering the rates of respiratory illnesses.

The respiratory syncytial virus is responsible for close to 80% of bronchiolitis cases in children, and respiratory syncytial virus infections generally occur in the winter months. It also increases the risk of asthma and wheezing. Here, the researchers aimed to understand whether children born during the COVID-19-associated lockdowns, when their exposure to the respiratory syncytial virus would have been low, had a lower risk of wheezing or asthma.

About the study

The present research included children born during the COVID-19-associated lockdown in Italy, which spanned the months of February to April 2020. The comparison cohort included children born in the same months during 2016 and 2017, for whom the data was obtained from the Pedianet database, which contains data from 150 pediatricians and family doctors in Italy.

The International Statistical Classification of Diseases Ninth Revision (ICD-9) codes in the health records were used to define wheezing, while the incidence rates of asthma were inferred from medications prescribed for asthma.

The researchers calculated the cumulative incidence of wheezing in person-months. Mediation analyses were conducted to determine the association between the onset of wheezing and whether the child was born during the COVID-19-related lockdown or the pre-pandemic winter months.

The study also examined how bronchiolitis mediated this association to determine the potential role of respiratory syncytial virus infections in increasing the risk of wheezing. All the estimations were adjusted for sociodemographic factors such as area deprivation index, sex, and geographic location.

Results

The study found that children born during the pandemic-enforced lockdowns had a lower requirement of respiratory medications and experienced fewer episodes of wheezing than children born during the same months but in the pre-pandemic years of 2016 and 2017.

The researchers included 2,192 children born during 2020 in the pandemic-associated lockdown months and over 3,800 children born before the pandemic. The two cohorts did not differ in area deprivation index scores, sex, or the occurrence of atopic disease.

The 30-month follow-up observations reported that the incidence of wheezing in the lockdown cohort was 9.4% (206 out of 2192 children), while that in the historical cohort was 15% (582 out of 3,889 children). The lockdown cohort saw a wheezing episode rate of 67.6 per 10,000 person-months, while the historical cohort experienced a wheezing episode rate of 110 every 10,000 person-months.

Furthermore, the number of bronchiolitis cases was almost negligible during the lockdown as compared to the occurrence of bronchiolitis during the pre-pandemic period (6.6 versus 82.4 per 10,000 person-months).

Additionally, the findings showed that the risk of wheezing was 44% lower in children born during the months when the COVID-19-associated lockdowns were implemented. The preventative measures implemented during the lockdown to limit the spread of SARS-CoV-2 were believed to lower the risk of wheezing by 30%, not accounting for the impact of bronchiolitis on wheezing risk.

The use of nebulized glucocorticosteroids and nebulized β₂ agonists was lower among children born during the lockdown as compared to those born in the pre-pandemic years, indicating that the incidence of asthma was also lower in children born during the COVID-19-related lockdown months.

While the present study was not able to ascertain the incidence of respiratory syncytial virus infections, given its retrospective nature, based on the findings from other extensive cohort studies, the authors believe that the prevention of respiratory syncytial virus infections during the early years of the infant lowers the five-year risk of asthma by 26%. These findings also highlight the importance of the universal immunoprophylaxis against respiratory syncytial virus.

Conclusions

Overall, the study found that children born during the COVID-19-associated lockdown months experienced significantly lowered rates of wheezing and asthma as compared to children born during the same months in previous years. The results suggest that protection from respiratory syncytial virus infections and bronchiolitis in the first year of growth could lower the risk of wheezing and asthma in the later years.