Dengue vaccines need long-term surveillance

On 8 June, Brazil temporarily suspended its Butantan-DV dengue vaccination rollout after reports of rare and unexpected adverse events during early implementation (1-3).This decision-an appropriate response to a safety signal-should not be interpreted as evidence that dengue vaccination has failed.Rather, it serves as a call to make dengue vaccine deployment more scientifically accountable.Every dengue vaccine rollout should be paired with active pharmacovigilance, transparent reporting, and post-licensure studies that can distinguish vaccine-related adverse events from severe dengue occurring after vaccination.The priority is not to retreat from dengue vaccination but to ensure that safety, effectiveness, and serotype-specific performance are monitored in real time.Dengue vaccine policy is unusually difficult to navigate because protection and risk may depend on prior immunity, age, transmission intensity, and which of the four dengue virus serotypes circulates after vaccination (4-8).Even if a vaccine is tetravalent (i.e., formulated to prevent infection by all four serotypes), the evidence available for public health decisions may remain uneven across serotypes and populations.This distinction matters most in low-transmission or newly affected regions, where many vaccine recipients may be seronegative, exposure may be delayed or sporadic, and the first post-vaccination infection may involve a serotype for which direct efficacy estimates are limited (6-8).