Updated Evidence Supports Current Vaccines Safety and Effectiveness

Ongoing peer-reviewed evidence supports the safety and effectiveness of vaccines against Covid-19, respiratory syncytial virus (RSV), and influenza during the 2025–2026 season. In a systematic review of 511 studies out of 17,263 identified references, Covid-19 mRNA vaccines targeting the XBB.1.5 subvariant showed pooled effectiveness against hospitalization of 46% from cohort studies and 50% from case–control studies among adults, with 37% effectiveness among immunocompromised adults. Vaccines targeting the KP.2 subvariant showed higher effectiveness at 68%. Maternal RSV vaccination, nirsevimab for infants, and RSV vaccines for adults aged 60 years or older demonstrated effectiveness of 68% or higher against hospitalization. Influenza vaccination had pooled effectiveness of 48% in adults aged 18–64 and 67% in children. Safety profiles were consistent with prior evaluations: myocarditis after Covid-19 vaccination occurred at rates of 1.3–3.1 per 100,000 doses in male adolescents (lower with longer dosing intervals), and the RSVpreF vaccine was associated with 18.2 excess cases of Guillain–Barré syndrome per million doses in older adults, without evidence of increased preterm birth when given at 32–36 weeks’ gestation. These findings underscore the continued benefit–risk balance favoring vaccination against major respiratory viruses in the U.S. Source: https://www.nejm.org/