Localized Inflammation in Dengue Vaccine-Induced Skin Rash Is Not Associated with Continuous Presence of Dengue Virus Genome.

Vaccination with the tetravalent live-attenuated dengue virus (DENV) vaccines TV003 and TV005 causes a mild, relatively localized erythematous maculopapular skin rash in most dengue-naïve vaccinees. Human challenge model DENV strains, DENV2Δ30 and DENV3Δ30, trigger a confluent skin rash over most of the body in most unvaccinated participants. To determine the etiology of these rashes, we performed in situ hybridization for DENV genome and assessed cellular infiltration by H&E staining in skin biopsies from humans infected with live-attenuated dengue vaccine DENV2Δ30 or DENV3Δ30 challenge strains. Sixty-three biopsies from 40 participants were included in the study, of which 43 biopsies from 32 patients contained intact RNA. Of these, 1 sample taken from a nonerythematous site from a DENV2Δ30-infected participant experiencing a rash was positive for DENV2 genome. Incidence and severity of lymphocytic infiltration were highest in rash biopsy samples than in those from noninvolved areas in participants experiencing a rash or from those taken from participants not experiencing a rash. These results indicate that the rash associated with infection with live-attenuated dengue vaccines or challenge strains is predominantly lymphocyte-driven perivascular dermal inflammation without local concomitant active viral replication.