HPV9 vaccination tied to reduced risk of juvenile idiopathic arthritis

Nine-valent human papillomavirus (HPV9) vaccination may protect against the development of juvenile idiopathic arthritis (JIA), and this benefit persists for at least 3 years, as shown in a retrospective study.

Researchers used data from the TriNetX US Collaborative Network. They identified girls ages 9–13 years who received their first HPV9 dose in either the prepandemic (2016-2019) or pandemic (2020-2023) period and matched them with unvaccinated controls. None of the participants had a previous JIA diagnosis, a history of antirheumatic drug use, or positive rheumatoid factor.

The main outcome of the incidence of new-onset JIA was tracked over 8 days to 36 months. Cox regression and Kaplan-Meier survival analysis were used in the analyses.

The analysis included a total of 99,243 vaccinated and 1.1 million control participants. Compared with controls, HPV9 recipients had a significantly lower risk of JIA at 36 months in both the prepandemic (hazard ratio [HR], 0.207; p<0.001) and the pandemic (HR, 0.287; p<0.001) periods. No increased risk was observed during the early postvaccination period.

The estimated cumulative probability of JIA did not significantly differ across the two periods both among HPV9 recipients (p=0.9) and among unvaccinated controls (p=0.238), indicating that COVID-19 did not exert any modifying effects.

Taken together, the findings reinforce the immunological safety of HPV9 and provide reassurance for adolescent vaccination programs, even in pandemic contexts, according to the researchers.