Humoral immune response to SARS-CoV-2 vaccines in patients with autoimmune rheumatic diseases

Background: Patients with autoimmune rheumatic diseases (ARD) are at increased risk of infection due to their impaired immune response, which also reduces vaccination efficacy. Although several studies have evaluated the serological response to SARS-CoV-2 mRNA-based vaccines in patients with ARD, limited information on immune responses to other vaccination platforms is available.

Aims: This observational prospective study aims to investigate the humoral immune response to different SARS-CoV-2 vaccines in patients with ARD.

Methods: Total 66 patients with ARD who were scheduled to receive any SARS-CoV-2 vaccine (Gam-COVID-Vac; AZD1222; BBIBP-CorV; mRNA-1273; BNT162b2 and Ad5-nCoV) were enrolled in the study. We analyzed the humoral immune response elicited against the spike receptor-binding-domain (RBD) of SARS-CoV-2 at 0 and 14 ± 2 d after the first vaccine dose and at 0 ± 1, 21-45, and 180 d after the second one. Titers were also measured in patients who received an additional dose of vaccine.

Results: After the second dose of the vaccine, 70.5 % experienced seroconversion. The type of vaccine affected serological responses. BBIBP-CorV resulted in lower seroconversion rates, while mixed vaccinations increased anti-RBD titers. Other factors impacting seroconversion were higher prednisone doses, biological therapy, and hypertension. Patients treated with Rituximab had the lowest seroconversion rate. Regression analysis revealed an 89.0 % lower probability of seroconversion for BBIBP-CorV recipients and an 88.0 % lower probability for those with hypertension. An additional dose increased seroconversion to 85.7 %.

Conclusions: Two-dose vaccination schemes exhibited a 70.5 % seroconversion rate to the SARS-CoV-2 vaccine. An additional dose increased this rate to 85.0 %. Reduced humoral immune responses were associated with BBIBP-CorV, prednisone higher doses, and biological therapy.