Although some reports have described isolated cases of immunoglobulin A vasculitis (IgAV) in children, researchers did not find evidence of a likely etiologic connection between vaccines and childhood-onset IgAV, according to study findings published in Pediatrics.

There are some reports that describe the development of IgAV in adults and children following vaccination, but there is a paucity of robust evidence using pharmaco-epidemiologic data to validate this relationship. Researchers aimed to explore whether vaccinations could be reliably linked to short-term IgAV risk in children.

Between 2011 and 2016, researchers enrolled patients <18 years (n=167; mean age at onset, 6.7years; 52% male) who had been diagnosed with IgAV and had complete immunization records for the year preceding vasculitis onset into a case-crossover analysis. The year before diagnosis was divided into a 3-month index period immediately preceding disease onset and 3 separate 3-month control periods comprising the 9-month stretch immediately preceding the index period. Vaccine exposure was compared between the index and control periods and odds ratios (ORs) were calculated using regression analyses. Results were stratified by age, sex, year and season of onset, infection history, and number and type of vaccines administered. Index and control periods of 1, 1.5, and 2 months were used for additional sensitivity analyses.

Of the 167 recruited participants, 42 children (25%; mean age at onset, 7.5 years; 57% male) who received ≥1 vaccine in the prior year and qualified for further analysis, while 125 children (75%; mean age at onset, 6.4 years; 50% male) did not meet this criterion. There were 15 patients (9% of initial enrollees) immunized during the index period and 4% to 7% immunized during the 3 control periods.

Upon analysis, the risk of developing IgAV within 3 months of vaccination had an OR of 1.6 (95% CI, 0.8-3.0). Additional sensitivity analyses of vaccination risk revealed 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) for the 1-, 1.5- and 2-month periods, respectively, prior to IgAV onset. There were non-significant trends that saw stronger correlations in boys (OR, 2.1; 95% CI, 1.0-4.8), children <5 years (OR, 1.8; 95% CI, 0.4-7.5), and winter onset (OR, 3.0; 95% CI, 0.6-14.9). No significant associations were uncovered following multiple stratifications. These results indicated that there was no significant risk (estimated at 5%) of developing IgAV within 3 months of standard childhood immunizations.

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Study strengths included a population-based, prospective enrollment regardless of immunization status, a large sample size, and likely generalizability to childhood IgAV. However, the researchers noted that the sample size was too small to be able to perform robust subgroup analyses or evaluate the risk for IgAV according to specific vaccinations.

“The results of our study are reassuring with regard to the risk of IgAV onset during the 3 months after vaccination in children,” concluded the authors. However, they also cautioned that “The importance of vaccine safety in terms of public health may justify further monitoring of the relation between vaccines and IgAV risk,” and recommended that future studies examine other environmental risk factors for IgAV.

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Reference

Piram M, Chiappe SG, Madhi F, Ulinski T, Mahr A. Vaccination and risk of childhood IgA vasculitisPediatrics. 2018;142(5):1-9.