Immunogenicity decay and case incidence six months post Sinovac-CoronaVac vaccine in autoimmune rheumatic diseases patients

The determination of durability and vaccine-associated protection is essential for booster doses strategies, however data on the stability of SARS-CoV-2 immunity are scarce. Here we assess anti-SARS-CoV-2 immunogenicity decay and incident cases six months after the 2nd dose of Sinovac-CoronaVac inactivated vaccine (D210) in 828 autoimmune rheumatic diseases patients compared with 207 age/sex-balanced control individuals. The primary outcome is the presence of anti-S1/S2 SARS-CoV-2 IgG at 6 months compared to 6 weeks after 2nd vaccine dose for decay evaluation. Secondary outcomes are presence of neutralizing antibodies, percent inhibition by neutralizing, geometric mean titers and cumulative incident cases at 6 months after 2nd dose. Anti-S1/S2 IgG positivity and titers reduce to 23.8% and 38% in patients (p p p p