OBJECTIVES : This study aims to assess the efficacy of Dengue Vaccine

METHODS : A systematic review with a meta-analysis was conducted using randomized controlled clinical trials published between 2000 and 2017 that were identified in the MEDLINE databases via PubMed, LILACS, Cochrane Library and EMBASE. The selection was performed by two reviewers independently, with disagreements resolved by a third reviewer. The meta-analysis using the random-effects model was performed. The bias risk assessment was independently performed by two reviewers (L.T.C.S. and B.T.) using the Cochrane Collaboration tool to assess the risk of bias from clinical trials [9]. The following criteria were evaluated: selection bias (random sequence generation and allocation concealment); performance bias (masking of participants and professionals); detection bias (masking of outcome assessors); friction bias (incomplete outcomes or losses) and reporting bias (reporting of selective outcome). For other biases, we evaluated the conflict of interest.

RESULTS : Seven clinical trials were included, with a total of 66,511 participants between the ages of 2 and 45 years. The efficacy of the vaccine as estimated at 44%, with a range from 25% to 59% and high heterogeneity (I=80.1%). The serotype-stratified meta-analysis was homogeneous, except for serotype 2, with a heterogeneity of 65%. Regarding the immunogenicity, most of the vaccinated individuals were previously immune to at least one serotype, with seropositivity varying in the studies from 37% to 81%.], All studies presented a high bias risk for conflict of interest. Two papers presented a high risk of bias for the masking of participants and professionals.

CONCLUSIONS : Compared with other commercially available vaccines, the dengue vaccine showed poor efficacy. Most of the vaccinated individuals had previous immunity for at least one serotype, which generated safety concerns in individuals without previous immunity. Vaccination may lead to an unwanted response in the mon-immune vaccinated subject, questioning the use for disease prevention.