Respiratory tract infections (RTIs) cause significant child morbidity and mortality. Periodical influenza vaccination and respiratory syncytial virus (RSV) prophylaxis can reduce this burden in risk groups. However, in the Caribbean, the optimal timing of these interventions is unclear due to a lack of epidemiological data. We aimed to investigate pathogens associated with RTI disease burden and pathogen specific seasonality in the Caribbean in the context of COVID-19 to achieve optimal timing of preventive measures.

We conducted a retrospective study using patient records and pathogen detection data from St. Maarten Medical Center from 1 September 2018 to 1 September 2023. We performed regression to associate pathogens with outcomes and seasonality.

RTI diagnoses accounted for 50.8% (N=7380) of outpatient cases and 28.0% (N=508) of inpatient cases. RSV and rhino/enterovirus were associated with more frequent oxygen requirement (OR 5.1 (95% CI 2.3 to 11) and OR 2.3 (95% CI 1.2 to 4.3), respectively) and tachypnoea/dyspnoea (OR 4.9 (95% CI 2.0 to 13) and OR 2.8 (95% CI 1.6 to 5.2), respectively) than other pathogens post-COVID-19. RSV consistently peaked during June/July and September/October, preceding RSV prophylaxis administration in October.

The overall burden on the healthcare system due to RTI visits and admissions was high. Higher disease severity was associated with RSV and rhino/enterovirus infections; therefore, universal RSV prophylaxis should be considered, and timing should be optimised based on seasonality.