Background Rheumatic diseases, including juvenile idiopathic arthritis, are chronic inflammatory conditions affecting children. There have been concerns regarding the potential role of live attenuated viral vaccines in triggering rheumatic diseases. This phase 2 trial aimed to investigate the association between two live attenuated viral vaccines and the development of rheumatic diseases in children.

Methods A randomized, controlled open-label trial was conducted involving children aged 1–12 years who were eligible to receive live attenuated viral vaccines for heterologous rVSV-ZEBOV-GP Ebola or varicella. Participants were randomly assigned to receive the vaccine. A muscle-skeleton examination, FBCs, ESR, CRP, HLA-B27, lgM, RF, and ANA were accessed on Days 0,1,2/3, 7, 14, 21, 28, 58, 180, and 365 routinely. The primary outcome was the development of rheumatic diseases, within the follow-up period.

Results 120 children were enrolled in the trial, with 80 in the rVSV-ZEBOV-GP group and 40 in the varicella group. The mean age at enrolment was 6.46 years, and the study population consisted of an equal distribution of gender. The follow-up period, days 1, 2/3, 7, 14, 21, 28, 58, 180, and 365 showed no significant differences in the incidence of rheumatic diseases between the two vaccines clinically. Some participants complained of arthralgia (1.9%), however, it was associated with plasmodium falciparum. For the rest of the inflammatory markers, analysis has been completed and will be available timely.

Conclusion In this phase 2 trial, there was no evidence to suggest that administering two live attenuated rVSV-ZEBOV Ebola and Varicella, was associated with a risk of rheumatic diseases in children. The noted pseudo-signs of rheumatic diseases like arthralgia and body ache were strongly linked to Malaria infection. These findings provide reassurance regarding the safety profile of rVSV-ZEBOV-GP Ebola and varicella concerning rheumatic diseases in children.