Dengue vaccines and serotype complexity: Why India needs a calibrated strategy.

India's approval of TAK-003 (Qdenga) on July 20, 2026, marks a defining moment in dengue prevention, yet four-serotype complexity demands a calibrated rather than uniform strategy. Built on a live-attenuated DENV-2 backbone, TAK-003 generates lower type-specific neutralising antibody titres - most critically against DENV-3 - an imbalance compounded by original antigenic sin, which may further limit cellular priming against DENV-3 and DENV-4. India's epidemiology amplifies these concerns: DENV-3 accounted for nearly 80% of typed cases in Bengaluru in 2024 - a regional signal, though serotype dominance varies across States - and large seronegative peri-urban populations remain vulnerable. NIH TV003-derived vaccines, including India's DengiAll in Phase 3, incorporate attenuated strains of all four serotypes, offering potentially broader immunity. TAK-003's demonstrated efficacy against severe dengue and hospitalisation - including in seronegative participants - makes it a valuable first-line tool. We argue for a phased, serotype-informed strategy: deploy TAK-003 now, while building surveillance capacity for vaccines with potentially broader serotype coverage.