RT Conference Proceedings T1 Evaluation of the efficacy and safety of the sars-cov-2 vaccine in patients with chronic inflammatory diseases treated with biological therapy A1 Calvo-Gutierrez, J. A1 Lopez-Medina, C. A1 Abalos-Aguilera, M. C. A1 Perez-Jimenez, A. B. A1 Ruiz-Vilchez, D. A1 Pilar, F. U. A1 Ortega-Castro, R. A1 Escudero-Contreras, A. A1 Collantes-Estevez, E. K1 RNA, Viral K1 Antirheumatic Agents K1 Immunoglobulin G K1 Rheumatology K1 Spike Glycoprotein, Coronavirus AB In the current situation of the SARS-CoV-2 pandemic, the Spanish Society of Rheumatology recommends vaccination of patients with chronic inflammatory diseases (CID) under treatment with biological DMARDs (bDMARDs). However, the data regarding the generation of protective antibody titers after mRNA vaccines in patients with CID is limited. The objective of this study was to determine the seroconversion rate and safety after the SARS-CoV-2 vaccine in patients with CID under treatment with bDMARDs. A cross-sectional observational study was conducted with 81 patients with CID from the HURS in Córdoba, who received full vaccination for SARS-CoV-2 (without having previously suffered from COVID-19 disease) according to national guidelines. A determination of specific IgG-type antibodies against the trimeric spike protein of SARS-CoV-2 was performed on all of them. The chemiluminescence technique with the kit was used in serum samples taken 4–5 weeks after administration of the second dose of the vaccine. Information about sociodemographic characteristics, disease, type of bDMARDs, concomitant treatments, and adverse effects after the second dose of the vaccine were collected in each patient. A total of 81 patients were included (mean age 59.5, 72.8% females). 50.6% of patients had RA, 17.3% SpA, 11% PsoA, and 18.5% other CID. 23.5% were under treatment with Rituximab, 38.8% antiTNF, 13.6% Tocilizumab, 9.9% Abatacept, 5% anti-JAK, and 14.2% under other treatments. Anti-SARS-CoV-2 antibodies and neutralizing activity were detected in 80% of study participants. Rituximab treatment was significantly associated with negative seroconversion in comparison with patients under antiTNF treatment (OR 84.0 [95% CI 12.9–1709.2]). No interaction was found between the bDMARDs treatment and the type of vaccine with regard to the seroconversion, nor between bDMARDs and concomitant synthetic DMARD. PB Bmj publishing group SN 0003-4967 YR 2022 FD 2022-05-23 LK http://hdl.handle.net/10668/20109 UL http://hdl.handle.net/10668/20109 LA en NO Gutierrez JC, López-Medina C, Ábalos-Aguilera MC, Jiménez ABP, Ruíz-Vilchez D, Pilar FU, et al. AB1149 Evaluation of the efficacy and safety of the sars-cov-2 vaccine in patients with chronic inflammatory diseases treated with biological therapy. Annals Of The Rheumatic Diseases [Internet]. 23 de mayo de 2022;81(Suppl 1):1691.2-1692. DS RISalud RD Oct 3, 2025