615 - Epidemiology of bronchiolitis among young children in central New York before and after the onset of the COVID-19 pandemic

The COVID-19 pandemic ignited a global decline in endemic respiratory virus circulation that resumed in 2021 with an inter-seasonal surge. This disrupted pattern has continued with an early and severe 2022 respiratory season.

Objective:

Here, we describe the epidemiology of acute bronchiolitis among children less than 5 years in central New York before and after the onset of the COVID-19 pandemic.

Design/Methods:

A retrospective, cohort study was conducted using data collected from the EMR of SUNY Upstate Medical Center. Clinical and sociodemographic data were collected October 2015 - December 2022 from medical encounters associated with appropriate ICD-10 codes. Respiratory seasons were defined by RSV percent positivity, i.e. 2 consecutive weeks with > 3% positivity with continued rise. Data for each completed respiratory season were compared and visualized via mosaic plots with statistical analysis performed using Pearson chi-square testing.

Results:

Of the 8,743 cases of bronchiolitis documented during the study period, 64% were tested and 40% confirmed positive for RSV. 

During the 2021 inter-seasonal surge:

• There were 163% more bronchiolitis cases than the prior 5 seasons


• The increase was seen across all care settings, with the greatest rise in the ED and outpatient settings (p< 0.001, Figure 1)


• The increase was seen across all age cohorts, with the greatest rise seen among children 12 months and older (p< 0.001, 0-11 months: +60%, 12-23 months: +163%, 24-35 months: +440%, 36-47 months: +628%, 48-59 months: +1035%)


• The proportion of bronchiolitis cases among Black and Asian children increased (p< 0.001, Figure 2)


• RSV bronchiolitis increased by 259% coinciding with an increase in all bronchiolitis cases and RSV testing, and a decrease in percent RSV positivity among all bronchiolitis cases (Figure 3)

The 2022 bronchiolitis season is ongoing; however, the current peak has surpassed 2021 across all care settings with RSV predominating (Figure 3).

Conclusion(s):

During the summer of 2021, the large increase in bronchiolitis cases correlated with the reemergence of circulating respiratory viruses. The 2022 peak has surpassed the 2021 peak, particularly among inpatient hospitalizations. The 2021 and 2022 peaks have unique characteristics that distinguish them from pre-pandemic peaks and each other.

Increased testing illustrates the true burden of RSV. This data highlights the critical need for RSV preventative and therapeutic agents. Ongoing surveillance to identify vulnerable populations and shifting patterns is needed to ensure equitable distribution once agents are available.