The following is a summary of “Immune Response to SARS-CoV-2 Third Vaccine in Patients With Rheumatoid Arthritis Who Had No Seroconversion After Primary 2-Dose Regimen With Inactivated or Vector-Based Vaccines” published in the December 2022 issue of Rheumatology by Isnardi, et al.

To evaluate the immunological response to a third dose of SARS-CoV-2 vaccination in rheumatoid arthritis (RA) patients with undetectable antibody titers following the main regimen of 2 doses. Patients with RA who had not achieved seroconversion after 2 doses of SARS-CoV-2 vaccine were eligible to receive a third dose of either an mRNA or vector-based vaccine. After the third dosing, researchers tested for anti-SARS-CoV-2 IgG antibodies, neutralizing activity, and T cell responses.

About 21 patients who didn’t have any kind of response were included. A quarter of those vaccinated were on glucocorticoids, and another 29% were taking biologic disease-modifying antirheumatic medicines (including 6 taking abatacept [ABA] and 4 taking rituximab [RTX]). There was just one person who got the ChAdOx1 nCoV-19 vaccine, while 95% got the BNT162b2 vaccine. About 91% of patients had detectable anti-SARS-CoV-2 IgG after the third treatment, and 76% had neutralizing activity. In a meta-analysis of randomized controlled trials, ABA and RTX were related with lower titers of neutralizing antibodies (median 3, IQR 0-20 vs 8, IQR 4-128; P=0.20) and the absence of neutralizing activity in 4 of 5 (80%) patients.

After the second dose, a specific T cell response was observed in 41% of patients, and after the third dose, that number jumped to 71%. A reduced frequency of T cell response was seen when ABA was used (33% vs 87%, P=0.03).  After a third dosage of the SARS-CoV-2 vaccination, 91% of patients in this RA group who had not seroconverted after the first two doses did so. Use of ABA was linked to a decrease in the occurrence of a targeted immune response.