In a recent study posted to the medRxiv* preprint server, researchers assessed the impact of the coronavirus disease 2019 (COVID-19) pandemic on the seasonal patterns of RSV (respiratory syncytial virus) infections among young children residing in the US (United States).

Background

Studies have reported that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has distorted the transmission of pulmonary viral diseases such as those caused by RSV. Elevated rates of RSV infection-related hospitalizations have been documented in 2022, especially among lower-aged children. However, the timing, duration, and magnitude of the RSV infection upsurge among lower aged-children have not been well-characterized.

About the study

In the present study, researchers evaluated changes in the patterns of RSV-caused diseases in the pediatric US population in relation to the COVID-19 pandemic on November 24, 2022.

The team analyzed population-level data from a real-time and national database comprising de-identified and aggregated EHRs (electronic health records) of 560 lakh individuals from 34 healthcare organizations residing in 50 US states using the TriNetX analytics platform. The characteristics and patterns of RSV-caused diseases in children aged ≤5.0 years and those aged ≤1.0 years were assessed between 2010 and November 2022.

RSV-positive and RSV-negative children characteristics were compared, and probable COVID-19-associated risk factors were identified. The month-wise incidence rates of RSV-infected children (evaluated based on novel cases among every one million individual-days) aged ≤5.0 years and those aged ≤1.0 years with prior medical consultation with healthcare organizations but no history of RSV infections were calculated.

Further, the team compared the characteristics of infected and uninfected children between May and November 2022. In addition, the monthly incidence rates by ethnicity, sex, and race, were determined. The characteristics compared included demographics, prior SARS-CoV-2 exposure, RSV-associated comorbidities, socio-economic health determinants (housing, psychosocial environments), and the status of COVID-19 vaccinations.

Results

Records for 12,507,431.0health consultations for children aged ≤1.0 years and 42,222,538.0 for those aged ≤5.0 years between 2010 and 23 November 2022 were analyzed. Between 2010 and 2019, a consistent trend was noted for the monthly RSV infection incidence rates among children aged ≤5.0 years was observed. Cases increased between September and November, peaked between December and January, reduced between February and April, and steadily reduced further from May to August.  

In 2019, a significant increase in the peak RSV infection incidence was observed compared to the prior calendar years (561 versus 335 RSV infection cases among every one million individual-days during December 2019 and December 2018). In 2019, more cases were reported during the summer season compared to those in previous years in prior years. During COVID-19, the seasonal trends in RSV infections were altered. During 2020, no seasonal alterations were observed, with consistently low incidence rates between May 2020 and April 2021 (four cases to 44.0 cases among every 1,000,000 individual-days) without any increase during the autumn and winter seasons.

In 2021, seasonality was observed at an earlier time compared to pre-COVID-19 years, with RSV infection incidence rates increasing from May to June (98.0 cases to 282.0 cases among every 1,000,000 individual-days, respectively), with a peak in August with 559.0 cases among every one million individual-days. The peak was followed by reductions from October onward (377 cases among every one million individual-days).

In 2021, the season of RSV infections widened to 9.0 months (between May 2021 and January 2022). The peak RSV infection incidence rates for 2019 and 2021 were comparable and significantly greater than those between 2010 and 2018.

During 2022, the trends were altered, with a steady rise continuing between May (138.0 cases among every one million individual-days) and November, with 1,027.0 cases among every 1,000,000 individual-days in November. The incidence rates were the greatest in 2022 compared to any prior years for peaks in 2021. The incidence rates among children aged ≤1.0 years followed the same patterns as those aged ≤5.0 years, but the rates were greater, with 1,447.0 cases among every one million individual-days, in November of the year 2022.

Between 2010 and 2021, significantly greater rates were observed among Blacks compared to Whites and ranged between nine percent and 44%, except for the 2011 to 2017 period, during which the rates were comparable. In November of 2022, differences in peak RSV infection incidence widened to 195.0% (2,135.0 cases and 723.0 cases among every one lakh individual-days among Blacks and Whites, respectively).

The peak incidence was greater among Hispanics than Whites, with larger differences between Whites and Blacks. No significant differences were observed in peak incidence between 2010 and 2021 by sex, and males showed significantly greater peak rates in November 2022.

Among RSV-infected children aged ≤5.0 years, 7,823 children contracted RSV. The RSV-positive children were significantly lower-aged, Blacks or Hispanics, with greater socio-economical health determinants and comorbidities such as preterm births, immunological diseases, chronic pulmonary disorders of perinatal origin, malnutrition, and Down syndrome, which increase RSV contracting risks. In addition, RSV-positive children had a greater prevalence of previous SARS-CoV-2 infections (19%).

Conclusion

Based on the study findings, the seasonal trends of RSV infections among young children were disrupted during the COVID-19 pandemic.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Written by

Pooja Toshniwal Paharia

Dr. based clinical-radiological diagnosis and management of oral lesions and conditions and associated maxillofacial disorders.