Analyzing Seasonal Trends of Respiratory Syncytial Virus Circulation Using Latin American National Surveillance Database during Pre- and Post-COVID-19 Pandemic.

Objectives: The COVID-19 pandemic disrupted respiratory syncytial virus (RSV) seasonality patterns globally. This study analyzed RSV seasonality trends in Latin America before, during, and after the pandemic.

Methods: An analysis of the Influenza Report of Pan American Health Organization (PAHO) sentinel surveillance reports was conducted across seven Latin American countries (Argentina, Brazil, Chile, Colombia, Dominican Republic, Honduras, Mexico) from January 2015 to September 2024. The study examined seasonality trends, testing rates, and RSV subtypes.

Results: RSV cases decreased substantially during 2020 across all countries. After the pandemic, RSV showed signs of returning to pre-pandemic seasonal trends with a modest shift (1-4 weeks) in peak timings across countries except for Mexico and Colombia. The duration of the RSV seasonality varied from 4 to 32 weeks across countries. Predominantly negative correlations between RSV and SARS-CoV-2 circulation were observed in most countries, suggesting potential viral interference mechanisms. RSV subtype A predominated in most countries after 2022.

Conclusions: RSV seasonality across Latin American countries is gradually returning to pre-pandemic patterns, with Southern Hemisphere countries showing more consistent recovery than equatorial regions. These findings highlight the importance of continuous surveillance, need for optimizing vaccination strategies and implementing early diagnosis techniques for better preventive measures.