activation of autoreactive B cells to secrete IgG anti-DNA autoantibodies.19,20 The adjuvants in the vaccine can also stimulate the production of polyclonal autoantibodies.21 These processes can either induce or exacerbate autoimmune diseases.
In this study, we found no significant relationship between most autoimmune adverse events and zoster vaccine. The odds of developing vasculitis, thrombocytopenia, GBS, demyelinating neurological conditions, and SLE were not significantly increased post immunization. However, we noticed increased odds of developing arthritis and alopecia after zoster vaccine, compared to age- and gender-matched controls, suggesting a possible association. The presentation of arthritis might have been secondary to serum sickness reaction to recent zoster vaccine, which contains bovine calf serum.22 Some cases of arthritis were assessed and diagnosed by rheumatologists. Physical examination and laboratory data, however, were either not available or incomplete for some cases of arthritis and alopecia. There have also been no published case reports in the scientific literature regarding the development of arthritis or alopecia after zoster vaccine. This association might be more formally evaluated by a long-term cohort study of patients immunized with zoster vaccine.
Being a live attenuated vaccine, there have been concerns about its use in patients with autoimmune diseases, who may
be immunosuppressed to a certain degree. However, recent studies have shown that zoster vaccine is relatively safe in such patients.23,24 Despite its benefits and safety, there is still low coverage of the vaccine. The CDC had previously reported that only 20.1% of elderly patients 60 years or older received herpes zoster vaccine in 2012.25 Overall, Caucasians aged 60 years or older had the highest vaccination rate (22.8%), followed by Asians (16.9%), African Americans (8.8%), and, lastly, Hispanics (8.7%).25 Possible barriers to widespread coverage include high financial costs as well as lack of patients’ awareness and physician’s recommendation.26
Our study utilized a case-control study method previously reported in the literature16 to evaluate cases in the VAERS database. Events with the abovementioned defined SAAEs form the cases in our study. They were matched in terms of age and gender to controls. For each autoimmune adverse event, we evaluated the exposure (zoster vaccine versus tetanus toxoid- containing vaccine) among all cases and controls to account for autoimmune side effects secondary to other vaccines, such as HBV and HPV vaccines. The VAERS Working Group of the CDC had previously stated that self-reported adverse events by patients accounted for less than 5% of the total cases.27 Most cases were confirmed by physician assessment. Information from the VAERS database is readily available and updated regularly in a timely fashion. However, the database has the potential
