Abstract
Background
The expansion of dengue vaccination strategies in Brazil, including the introduction of the Butantan dengue vaccine (DV), has reinforced the importance of post-marketing safety surveillance. We aimed to characterize reporting patterns of adverse events following immunization (AEFIs) and immunization errors associated with dengue vaccines in Brazil.Methods
We conducted a nationwide retrospective observational study using records of AEFIs associated with dengue vaccines reported to the Brazilian Ministry of Health through June 2026. AEFIs were classified as serious or non-serious according to national surveillance criteria, and immunization errors were analyzed separately.Results
Among 47,666 individuals with reported AEFIs or immunization errors following dengue vaccination, 525 (1.1%) experienced at least one serious AEFI, 43,043 (90.3%) reported non-serious AEFIs, and 4098 (8.6%) were classified as immunization errors. Serious AEFIs were uncommon across vaccine platforms. Among recipients of Butantan-DV, the most frequent serious AEFIs were skin manifestations, central nervous system symptoms, and myalgia or arthralgia. Among recipients of other dengue vaccines, skin manifestations, anaphylaxis or bronchospasm, and respiratory symptoms predominated. Non-serious AEFIs were mainly exanthema, headache, and pruritus. Immunization errors were primarily related to inappropriate age at vaccination, shortened intervals between doses, and incorrect routes of administration. Reporting rates increased during the expansion of dengue vaccination activities in 2026.Conclusions
In this nationwide pharmacovigilance study, dengue vaccines demonstrated a favorable safety profile, with serious adverse events accounting for only a small proportion of reported events. These findings support the implementation of dengue vaccination programs while reinforcing the importance of ongoing surveillance to identify rare safety signals and reduce preventable immunization errors.