581 - Incidence of Respiratory Syncytial Virus infections in the main pediatric hospital in British Columbia, Canada from September 1st to December 31st, 2021.​

Poster Number: 581
Publication Number: 581.417

Marina Vineta Paramo, BC Children's Hospital, Vancouver, BC, Canada; Rui Yang Xu, University of British Columbia Faculty of Medicine, Richmond, BC, Canada; Sudhakar Palanisamy, BC Children's hospital, Vancouver, BC, Canada; Frederic Reicherz, University of British Columbia Faculty of Medicine, Vancouver, BC, Canada; Jocelyn A. Srigley, University of British Columbia Faculty of Medicine, Vancouver, BC, Canada; Alfonso Solimano, University of British Columbia Faculty of Medicine, Vancouver, BC, Canada; Bahaa Abu Raya, University of British Columbia Faculty of Medicine, Vancouver, BC, Canada; Pascal M. Lavoie, University of British Columbia Faculty of Medicine, Vancouver, BC, Canada

Background:

Background: Respiratory Syncytial Virus (RSV) infections nearly disappeared during the COVID-19 pandemic in the context of physical distancing measures, with only 11 cases in British Columbia (BC), Canada between August 2020 and July 2021 compared to an average of 1750 cases per season in the previous 3 seasons. In parallel, we reported a profound loss in RSV neutralizing antibodies in women of childbearing age and infants in the spring of 2021, compared to previous years (Reicherz F et al., submitted).

Objective: To report RSV cases and hospitalizations in children less than 36 months of age at BC Children’s and Women’s Health Centre (BC C&W) in Vancouver, BC, during the early 2021-2022 RSV season, from September 1st to December 31st, 2021.

Design/Methods: Prospective descriptive cohort study of children less than 36 months of age who tested positive for RSV by nucleic acid testing at BC C&W. Data were compared to three previous RSV seasons (2017-2018, 2018-2019, 2019-2020) for the same period coverage. Groups were compared by analysis of variance (ANOVA) for continuous variables and Chi-square for categorical variables.

Results: During this interim study period, 606 children tested positive for RSV. This was higher compared to the same period for other seasons, with 52 for 2017-2018, 81 cases for 2018-2019 and 93 cases for 2019-2020 (Figure 1). Among the cases, the median age was significantly higher in 2021-2022 (12.65 months; IQR 19.65), compared to 2017-2018 (4.65 months; IQR 9.82), 2018-2019 (5.35 months; IQR 15.71) and 2019-2020 (8.32 months; IQR 14.43)(Figure 2). The hospitalized cases were 105 for this season, with a hospitalization rate of 14.77 admitted cases per 100 cases (Figure 3). There were no differences in the length of hospitalization nor age of admitted cases between seasons. Still, children admitted to the intensive care unit in this season was significantly higher compared to previous seasons (Figure 3).Conclusion(s): BC is experiencing an atypical RSV season, with a considerable increase in RSV infections in the early 2021-2022 season. The median age at diagnosis for RSV cases was significantly higher this season compared to previous seasons. The total hospitalized cases were higher in the current season, despite a lower hospitalization rate. This might be explained by the large number of positive cases and its older distribution. Proper follow up of this season will guide hospital planning and prevention programs. Further studies are required to understand immunological and epidemiological factors influencing this change in the trend of RSV epidemic after the COVID-19 pandemic.
RSV cases in children < 3 years old at BC C&WLine plot for RSV monthly cases diagnosed at BC C&W for each season
Age of RSV cases in children < 3 years old at BC C&WBox & whiskers plot for age at diagnosis of an RSV infection at BC C&W from September 1st to December 31st for each season. Whiskers show minimum and maximum values.
P values obtained from ANOVA comparison.