Humoral Immune Response to Sars-Cov-2 Third Vaccine in Patients with Autoimmune Rheumatic Diseases without Seroconversion after the Initial 2-Dose Regimen

ABSTRACT

Objectives: To evaluate the humoral immune response to the third dose (booster) of vaccine against SARS-CoV-2 in patients with autoimmune rheumatic diseases who were seronegative after a two-dose regimen. Method(s) Observational study. Patients with autoimmune rheumatic diseases who had not achieved seroconversion after a two-dose vaccine schedule against SARS-CoV-2 were included. To assess the humoral immune response, anti-RBD IgG (S protein receptor binding domain) neutralizing antibody titers were determined by ELISA (cutoff titer 200). The determination was made between 30 to 45 days after the third dose. Result(s) From 66 patients who received SARS-CoV-2 vaccination, 18 patients (29.5%) were seronegative after a two-dose schedule. 61% had SLE, 77% had comorbidities (61% with hypertension, p = 0.03). Patients were on treatment 10 with prednisone (8 with doses greater than 10 mg/d, p = 0.01), 10 with hydroxychloroquine, one with methotrexate, one with leflunomide, four with azathioprine, five with my cophenolatemofetil and five with rituximab (they are the total number of non-responders on biological treatment, p = 0.03). Regarding the primary vaccination regimen, 11 received BBIBP-CorV (p = 0.01), 5 AZD1222, 1 Gam-COVID-Vac and 1 mRNA1273/Gam-COVID-Vac heterologous scheme. Of these 18 non-responders, 14 received a third dose;nine patients (62%) presented anti-RBD IgG detectable. Of the five patients who did not respond to the booster vaccination, three had received BBIBP-CorV as the initial schedule and the vaccines applied as a third dose were Ad5-nCoV (1), BNT162b2 (1), AZD 1222 (2) and Gam-COVID-Vac (1). They were being treated with rituximab (2), azathioprine (2) and mycophenolate mofetil (1). Treatment with higher doses of prednisone was the only factor associated with non-seroconversion to the third dose (8 +/- 4.5;p 0.02). Conclusion(s) The third dose of SARS-CoV-2 vaccine allowed to improve the serological response to vaccination, achieving a seroconversion of 62% in this group of patients.