Objectives
To assess immunogenicity of a heterologous 4th dose of a mRNA (BNT162b2) SARS-CoV-2 vaccine in autoimmune rheumatic diseases (ARD) patients with poor/non-response to inactivated vaccine (Sinovac-CoronaVac).
Methods
164 ARD patients who were COVID-19 poor/non-responders (negative anti-SARS-CoV-2 S1/S2 IgG and/or neutralising antibodies—NAb) to the 3rd dose of Sinovac-CoronaVac received an additional heterologous dose of mRNA (BNT162b2) three months after last dose. IgG and NAb were evaluated before and after the 4th dose.
Results
Significant increases were observed after 4th dose in IgG (66.4% vs 95.1%, p< 0.001), NAb positivity (5.5% vs 83.5%, p< 0.001) and GMT (29.5 vs 215.8 AU/ml, p< 0.001), and 28 (17.1%) remained poor/non-responders. Patients with negative IgG after 4th dose were more frequently under rituximab (p= 0.001). Negative NAb was associated with older age (p= 0.015), rheumatoid arthritis (p= 0.002), systemic sclerosis (p= 0.026), leflunomide (p= 0.016), and rituximab use (p= 0.007). In multiple logistic regression analysis, prednisone dose ≥7.5 mg/day (OR = 0.34; p= 0.047), leflunomide (OR = 0.32, p= 0.036) and rituximab use (OR = 0.19, p= 0.022) were independently associated with negative NAb after the 4th vaccine dose.
Conclusions
This is the largest study to provide evidence of a remarkable humoral response after the 4th dose of heterologous mRNA SARS-CoV-2 vaccination in ARD patients with poor/no-response to the 3rd dose of an inactivated vaccine. We further identified that treatment, particularly rituximab and prednisone, impaired antibody response to this additional dose.
Trial registration
ClinicalTrials.gov, https://clinicaltrials.gov, CoronavRheum #NCT04754698