Vaccination and Risk of Childhood IgA Vasculitis

Abstract

BACKGROUND AND OBJECTIVES: Immunoglobulin A vasculitis (IgAV) might develop after vaccination. However, this potential relationship is essentially based on case reports, and robust pharmaco-epidemiologic data are scarce. We aimed to investigate the effect of vaccination on short-term risk of IgAV in children. METHODS: We enrolled children <18 years old with IgAV seen in 5 pediatric departments from 2011 to 2016. Data on vaccinations administered during the year preceding IgAV onset were collected from immunization records. With a case-crossover method and by using conditional logistic-regression analyses, odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by comparing vaccine exposure during the 3-month “index period” immediately preceding IgAV onset to that during 3 consecutive 3-month “control” periods immediately before the index period. Stratifications by season, year of onset, infection history, age, sex, type, or number of vaccines were performed. Sensitivity analyses used 1-, 1.5-, or 2-month index and control periods. RESULTS: Among 167 children (mean age: 6.7 years) enrolled, 42 (25%) received ≥1 vaccine during the year before IgAV onset. Fifteen (9%) children were vaccinated during the 3-month index period as compared with 4% to 7% during the 3 control periods. The OR for IgAV occurring within the 3 months after vaccination was 1.6 (95% CI: 0.8–3.0). Analyses of IgAV risk within 1, 1.5, or 2 months of vaccination yielded ORs of 1.4 (95% CI: 0.5–3.5), 1.4 (95% CI: 0.6–3.2), and 1.3 (95% CI: 0.6–2.6), respectively. Stratifications revealed no significant association. CONCLUSIONS: Vaccination may not be a major etiological factor of childhood IgAV.