Autoimmunity and hepatitis A vaccine in children.

Background: Universal vaccination remains the most effective way of preventing the spread of many infectious diseases. Although most adverse effects attributed to vaccines are mild, rare reactions such as autoimmunity do occur.
Objectives: We aimed to evaluate the possible role played by hepatitis A vaccine (HAV) in inducing the synthesis of autoantibodies. The study included 40 healthy children vaccinated with 2 doses of HAV at a 6-month interval. The children were investigated for autoantibodies including anti-nuclear antibodies (ANAs), anti-smooth muscle antibodies, anti-nDNA, anti-microsomal antibodies, anti-cardiolipin (aCL) immunoglobulin (Ig) M/IgG, anti-ds DNA, ANA profile, and anti-neutrophil cytoplasmic antibody profile.
Results: One month after the first dose, ANAs at a titer of 1:100 and aCL IgG at 23.7 IgM phospholipid units were detected in 4 children and 1 child, respectively. Of the ANA-positive children, 1 also had ASMA positivity, and another had perinuclear and cytoplasmic ANCA positivity. After the second dose, 3 of the children had aCL IgM. In addition, 2 distinct children had positive anti-thyroid microsomal antibodies and ANA after the second dose. The presence of these autoantibodies following vaccination was statistically significant (P = .002). At month 12 of the study, only 2 children continued to be ANA-positive at the same titer as after the first vaccine dose.
Conclusions: Although HAV can induce the production of autoantibodies, none of the children developed autoimmune disorders. Long-term follow up is necessary to check whether autoimmune disorders develop in children who still have ANA. Genetic, immunological, environmental, and hormonal factors are also important in the development of vaccine-induced autoimmunity.