[Comment] RSV prevention: public health lessons from the southern hemisphere

The NIRSE-CL study by Juan Pablo Torres and colleagues,1 published in The Lancet Infectious Diseases, is a landmark analysis of the first nationwide implementation of nirsevimab in the southern hemisphere. In Chile's 2024 respiratory syncytial virus (RSV) season, 145 087 infants (coverage of 94%) were immunised with nirsevimab through a universal immunisation campaign. This effort was associated with substantial effectiveness of nirsevimab against hospitalisation for RSV-related lower respiratory tract infection (LRTI; 76·41% [95% CI 72·57–79·72]), severe RSV requiring ICU admission (84·94% [79·47–88·95]), all-cause LRTI hospitalisations (66·50% [61·97–70·50]), and all-cause hospitalisations (47·90% [44·35–51·21]).