Inactivated SARS-CoV-2 vaccine in primary Sjögren's syndrome: humoral response, safety, and effects on disease activity

Introduction: There is no study specifically focused on SARS-CoV-2 vaccine in primary Sjögren's syndrome (pSS).

Objectives: To assess the immunogenicity, safety, possible effects on disease activity, and autoantibody profile of the Sinovac-CoronaVac vaccine in pSS.

Methods: Fifty-one pSS patients and 102 sex- and age-balanced controls without autoimmune diseases were included in a prospective phase 4 trial of the Sinovac-CoronaVac vaccine (two doses 28 days apart, D0/D28). Participants were assessed in three face-to-face visits (D0/D28 and six weeks after the 2nd dose (D69)) regarding adverse effects; clinical EULAR Sjögren's Syndrome Disease Activity Index (clinESSDAI); anti-SARS-CoV-2 S1/S2 IgG (seroconversion (SC) and geometric mean titers (GMT)); neutralizing antibodies (NAb); and pSS autoantibody profile.

Results: Patients and controls had comparable female sex frequency (98.0% vs. 98.0%, p = 1.000) and mean age (53.5 ± 11.7 vs. 53.4 ± 11.4 years, p = 0.924), respectively. On D69, pSS patients presented moderate SC (67.5% vs. 93.0%, p < 0.001) and GMT (22.5 (95% CI 14.6-34.5) vs. 59.6 (95% CI 51.1-69.4) AU/mL, p < 0.001) of anti-SARS-CoV-2 S1/S2 IgG but lower than controls, and also, moderate NAb frequency (52.5% vs. 73.3%, p = 0.021) but lower than controls. Median neutralizing activity on D69 was comparable in pSS (58.6% (IQR 43.7-63.6)) and controls (64% (IQR 46.4-81.1)) (p = 0.219). Adverse events were mild. clinESSDAI and anti-Ro(SS-A)/anti-La(SS-B) levels were stable throughout the study (p > 0.05).

Conclusion: Sinovac-CoronaVac vaccine is safe in pSS, without a deleterious impact on disease activity, and has a moderate short-term humoral response, though lower than controls. Thus, a booster dose needs to be studied in these patients.

Trial registration: ClinicalTrials.gov Identifier: NCT04754698. Key Points • Sinovac-CoronaVac vaccine is safe in pSS, without a detrimental effect on systemic disease activity, and has a moderate short-term humoral response • A booster dose should be considered in these patients.