Carolina A. Isnardi, Osvaldo L. Cerda, Margarita Landi, Leonel Cruces, Emilce E. Schneeberger, Claudia Calle Montoro, María Agustina Alfaro, Brian M. Roldán, Andrea B. Gómez Vara, Pamela Giorgis, Roberto Alejandro Ezquer, María G. Crespo Rocha, Camila R. Reyes Gómez, Mária de los Ángeles Correa, Marcos G. Rosemffet, Virginia Carrizo Abarza, Santiago Catalan Pellet, Miguel Perandones, Cecilia Reimundes, Yesica Longueira, Gabriela Turk, María Florencia Quiroga, Natalia Laufer, Rosana Quintana, María Celina de la Vega, Nicolás Kreplak, Marina Pifano, Pablo Maid, Guillermo J. Pons-Estel, and Gustavo Citera
ObjectiveThe aim of this study was to assess the immune response after a third dose of SARS-CoV-2 vaccine in patients with rheumatoid arthritis (RA) with undetectable antibody titers after the primary regimen of 2 doses.MethodsPatients with RA with no seroconversion after 2 doses of SARS-CoV-2 vaccine and who received a third dose of either an mRNA or vector-based vaccine were included. Anti-SARS-CoV-2 IgG antibodies, neutralizing activity, and T cell responses were assessed after the third dose.ResultsA total of 21 nonresponder patients were included. At the time of vaccination, 29% were receiving glucocorticoids and 85% biologic disease-modifying antirheumatic drugs (including 6 taking abatacept [ABA] and 4 taking rituximab [RTX]). The majority (95%) received the BNT162b2 vaccine and only one of them received the ChAdOx1 nCoV-19 vaccine. After the third dose, 91% of the patients presented detectable anti-SARS-CoV-2 IgG and 76% showed neutralizing activity. Compared to other treatments, ABA and RTX were associated with the absence of neutralizing activity in 4 out of 5 (80%) patients and lower titers of neutralizing antibodies (median 3, IQR 0-20 vs 8, IQR 4-128;P= 0.20). Specific T cell response was detected in 41% of all patients after the second dose, increasing to 71% after the third dose. The use of ABA was associated with a lower frequency of T cell response (33% vs 87%,P= 0.03).ConclusionIn this RA cohort, 91% of patients who failed to seroconvert after 2 doses of SARS-CoV-2 vaccine presented detectable anti-SARS-CoV-2 IgG after a third dose. The use of ABA was associated with a lower frequency of specific T cell response.