Background/Purpose: The importance and efficacy of mRNA COVID-19 vaccination in coping with the pandemic are well established, but inconsistencies remain in the data regarding side effects, especially in patients with rheumatic diseases treated with immunosuppressive therapy.

We aimed to assess the effect of immunosuppressive therapy on the incidence of Herpes Zoster (HZ) in patients with psoriatic arthritis (PsA) and ankylosing spondylitis (AS) after each of the three doses of the BNT162b2 mRNA vaccine compared to HZ incidence in a similar time period two years prior to vaccination.

Methods: The database of Clalit Health Services, the largest health care provider of approximately 4.7 million members in Israel, was retrospectively analyzed for patients with a diagnosis of PsA and AS starting from 12/2018 and who later received 3 doses of the BNT162b2 mRNA vaccine in a national vaccination campaign from 12/2020-12/2021. For each individual, data on demographic, socioeconomic, and selected chronic comorbidities, as well as use of glucocorticosteroids, conventional/ biologic/ targeted-synthetic disease-modifying anti-rheumatic drugs (DMARDs) and previous HZ vaccination status were retrieved.

The incidence of HZ events was calculated during the 6 weeks following each of the three mRNA COVID-19 vaccine doses and compared to a similar time period within this group of patients two years prior by NcNemar test, and also relative to fully-vaccinated controls from the general population matched by sex and age at 1:10 ratio. For each SpA patient, multivariable logistic regression was used to assess for any association between DMARD use within 3 months prior to each HZ event and HZ reactivation risk relative to SpA patients not on these medications.

Results: The study population consisted of 6460 SpA patients, 4648 (72.0 %) with PsA, 1812 (28.0%) with AS and 115 (1.8%) with both PsA and AS with a mean age of 57.6±15.0 years, of whom 3107 (48.1%) male. Of SpA patients, 18.2% (n=1173), 35.5% (n=2293), and 1.2% (n=79) were on cDMARDs, bDMARDs, and tsDMARDs, respectively. The incidence of HZ events was higher among SpA patients in comparison to the general population both pre- (p=0.004) and post- (p=0.027) mRNA COVID-19 vaccination, even after controlling for multiple covariates, with no significant difference in HZ reactivation occurring in the PsA vs AS subgroups pre- and post mRNA vaccination. The number of HZ events was not increased in SpA patients with HZ events who received bDMARDs (p=0.372), TNF-α inhibitors in particular (p=0.095), or cDMARDs (p=0.365) in comparison to patients not on these medications (too few HZ cases occurred in patients on tsDMARDs to allow for statistical analysis).

Conclusion: The risk of HZ after each one of the three BNT162b2 mRNA vaccine doses was not increased in PsA and AS patients compared to a similar time period two years prior to vaccination, and was not influenced by the type of DMARD used.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/analysis-of-the-effects-of-immunosuppressive-therapy-on-herpes-zoster-events-after-each-of-three-doses-of-the-bnt162b2-mrna-vaccine-in-patients-with-spondyloarthritis-spa/