Fourth dose of BNT162b2 vaccine for patients with autoimmune rheumatic diseases in a nationwide setting

Objective The effectiveness of COVID-19 vaccinations wanes due to immune evasion by the B.1.1.529 (Omicron) variant and diminished antibody titres over time. We aimed to evaluate the benefit of a fourth vaccination dose in patients with autoimmune rheumatic diseases (ARDs). Methods This retrospective analysis included ARD patients aged 18 years or older and members of Clalit Health Services in Israel (which at the time of the study insured 52% of the entire population), and covered the period from 16 January 2022 to 31 March 2022, when the predominant SARS-CoV-2 variant was Omicron. We compared patients without previous COVID-19 infection who had received three doses of the BNT162b2 vaccine (the control group) with those who had received the fourth dose. The primary outcome was COVID-19 infection, which was analysed using multivariate Cox regression in the entire cohort and within ARD subgroups. Secondary outcomes were COVID-19-related hospitalizations and COVID-19-related death. Results We included 43 748 ARD patients, of whom 27 766 and 15 982 were in the control and fourth vaccination groups, respectively. COVID-19 infection occurred in 6942 (25.0%) of the control group and 1754 (11.0%) of the fourth dose group (P < 0.001). Patients vaccinated with the fourth dose had a lower risk of COVID-19 infection than the entire cohort [Hazard Ratio (HR) 0.54, 95% CI 0.52, 0.58] and throughout every subgroup regardless of the baseline characteristic or medical treatment, except for rituximab. A similar association was observed for risk of COVID-19-related hospitalization (HR 0.36, 95% CI 0.22, 0.61) and of COVID-19-related death (HR 0.41, 95% CI 0.24, 0.71). Conclusion A fourth BNT162b2 vaccination of ARD patients was associated with favourable outcomes compared with three doses among patients with no history of COVID-19 infection.