September 10, 2026

Influenza

Early Antiviral Therapy in Pediatric Outpatients and Risk of Influenza-Related Hospitalization
These are the results of a multicenter, age- and season-matched, retrospective case-control study that included all pediatric outpatients with laboratory-confirmed influenza who sought care at the participating hospitals between 2020 and 2023. The effectiveness of early antiviral therapy (initiated within 48 hours of symptom onset, compared with delayed or no use) was estimated using conditional logistic regression. Subgroup analyses were performed for children aged 5 years or younger and older than 5 years. Among 1,492 children (354 cases and 1,138 controls; mean age, 7.1 years), early antiviral therapy was associated with an 81% lower risk of hospitalization overall (adjusted odds ratio [aOR], 0.19; 95% CI, 0.14–0.27), with similar protection among children aged 5 years or younger (aOR, 0.19; 95% CI, 0.12–0.31) and older than 5 years (aOR, 0.15; 95% CI, 0.09–0.25). The effect remained robust across sensitivity analyses by antiviral agent, with E-values up to 10.0 (range, 9.47–19.49 across subgroups).

COVID: Active Vaccination/Immunity

COVID-19 Vaccination and Risk of Post–COVID-19 Cardiovascular Disease: A Population-Based Cohort and Target Trial Emulation Study
These are the results of a statewide study that used linked administrative health data for 2,391,456 adults in Victoria, Australia (2019–2025). Associations of pre- or post-infection vaccination with major adverse cardiovascular events (MACE; primary outcome), stroke, heart failure, acute myocardial infarction (AMI), acute coronary syndrome (ACS), atrial fibrillation (AF), and venous thromboembolism (VTE) were evaluated. Vaccination was associated with lower hazards of MACE and all secondary outcomes. Estimated absolute risk reductions for MACE were 0.21% with pre-infection vaccination and 0.24% with post-infection vaccination. Three or more vaccine doses were associated with progressively lower hazards across cardiovascular outcomes. Mediation analysis suggested that approximately 68% of the estimated association between vaccination and lower post-COVID cardiovascular risk was not explained by prevention of SARS-CoV-2 infection.