India’s first dengue vaccine arrives with a crucial safety caveat

India has approved its first domestically developed dengue vaccine, marking a significant step in the fight against a disease that infects millions each year. However, the vaccine comes with a critical safety caveat: it is recommended only for people who have already been infected with dengue at least once. The decision follows large-scale clinical trials that showed the vaccine is safe and effective in preventing severe dengue in seropositive individuals—those with prior infection. For seronegative individuals, the vaccine could potentially increase the risk of severe disease upon later infection, a concern similar to that seen with an earlier international dengue vaccine. The Indian drug regulator has therefore mandated that the vaccine be administered only after a confirmatory test for past infection, or in settings where prior infection can be reliably established. Public health experts say this restriction is necessary to avoid harm, but it also creates logistical challenges for mass vaccination campaigns. The vaccine will initially be available through private hospitals and clinics, with a government rollout expected once screening protocols are standardized. For now, the cautious approval offers hope to millions who have already battled dengue, while leaving unanswered questions about how to protect those who have never been infected.