Humoral immunogenicity of mRNA booster after heterogenous CoronaVac-ChAdOx1 nCoV-19 or homologous ChAdOx1 nCoV-19 vaccine in autoimmune rheumatic diseases patients

ABSTRACT

Background/Purpose: The immunogenicity data of mRNA SARS-CoV- 2 vaccine boosted after completed primary series beyond mRNA vaccine in autoimmune rheumatic disease (ARDs) patients is sparse. We report the vaccine immunogenicity of SAR-CoV2 mRNA vaccine booting after completed heterologous CoronaVac followed by ChAdOx1 nCoV-19 (SV-AZ) or homologous ChAdOx1 nCoV-19 vaccination (AZ-AZ). Method(s) The levels of SARS-CoV- 2 anti-RBD IgG were evaluated at one and three months after mRNA vaccine booster in adults with ARDs who completed the heterologous CoronaVac-ChAdOx1 nCoV-19 vaccine (n = 19) or homologous ChAdOx1 nCoV-19 (n = 13) within 90-180 days. All patients were received at least one immunosuppressive drug as follows prednisolone <20 mg/day, methotrexate >=10 mg/week, azathioprine >=50 mg/day, mycophenolate mofetil >=1,000 mg/day, or leflunomide >=10 mg/day, as a stable dose for a month prior vaccination. Anti-RBD antibody was measured. Seropositivity was defined as IgG >=42 binding antibody units (BAU)/ mL. Disease activity was evaluated. Result(s) Among 33 ARDs, 78.8% were female, mean (SD) age was 42.9 years. Half of them were SLE (54.5%). Most patients received corticosteroid (75.8%), mean (IQR) dose of 7.5 (5, 7.5) mg/day of prednisolone. The immunosuppressive drugs used were as follows;azathioprine (45.5%), methotrexate (39.4%) and mycophenolate mofetil (21.2%). The anti-RBD IgG was positive in all SV-AZ group while one patient in AZ-AZ who received mycophenolate mofetil was seronegative. At one-month post mRNA booster, the median (IQR) anti-RBD IgG levels trended to be lower among patients with AZ-AZ than among SV-AZ primary series (1867.8 [591.6, 2548.6] vs. 3735.8 [2347.9, 5014.0] BAU/mL, P = 0.061). Mean (SD) anti-RBD IgG level in the AZ-AZ group was significantly lower than SV-AZ group at three-month post mRNA boosters (597.8 [735.5] vs. 1609.9 [828.4] BAU/mL, P = 0.003). Disease flare-ups occurred in six patients (18.2%), and all were minor flares. Conclusion(s) Our findings demonstrated satisfactory humoral immunogenicity of mRNA booster after primary series with the vaccine strategies rather than mRNA platform. SAR-CoV2 vaccine-induced immunity trend to lower in AZ-AZ primary series. The fourth dose in this subgroup might be a consideration without delay. However, this finding needs to be confirmed by a larger study. (Table Presented).