Exploring Dengue Infection in a Vaccinated Individual: Preliminary Molecular Diagnosis and Sequencing Insights

Abstract

This study examines a case involving a 7-year-old child who developed dengue symptoms following Qdenga vaccination. Despite initial negative diagnostic results, molecular analysis confirmed an infection with DENV4. Next-generation sequencing detected viral RNA from both DENV2 and DENV4 serotypes, which were identified as vaccine-derived strains using specific primers. Phylogenetic analysis further confirmed that these sequences belonged to the Qdenga vaccine rather than circulating wild-type viruses. This case underscores the critical need for precise diagnostic interpretation in vaccinated individuals to avoid misdiagnosis and to strengthen public health surveillance. A comprehensive understanding of vaccine-induced viremia is essential for refining dengue surveillance, improving diagnostic accuracy, and informing public health strategies in endemic regions.

Keywords: DENV monitoring; genomic surveillance; next-generation sequencing; vaccine breakthrough.

Figure 1

Phylogenetic reconstruction of DENV2 and DENV4. (a) Midpoint rooted maximum-likelihood phylogeny of distinct DENV2 genotypes, highlighting our newly generated DENV2-V sequence from Minas Gerais (EPI_ISL_19365344) and the Takeda vaccine-strain KU725663. The inset at the bottom left of panel shows the genome coverage retrieved from the pathogen, with a total genome length of 10,646 base pairs, covering the complete CDS (coding sequence) of the virus. (b) Midpoint rooted maximum-likelihood phylogeny of distinct DENV4 genotypes, highlighting our newly generated DENV4-II sequence from Minas Gerais (EPI_ISL_19365345) and the Takeda vaccine-strain KX812530.The inset at the bottom right of panel represents the genome coverage for the DENV4 sequence retrieved from the pathogen, displaying a genome length of 1924 base pairs, specifically covering the prM/E region of the genome.