Background: Patients with rheumatic diseases (RD) have been excluded from SARS-CoV-2 vaccine trials. Though data appear to show safety and efficacy, mostly evidence remains in mRNA vaccines. However in our country, adenovirus and inactivated vaccines, as well as heterologous schemes are frequently used.

Objectives: To describe clinical characteristics and outcomes of SARS-CoV-2 infection after vaccination in patients with RD from de the SAR-CoVAC registry and to compare them with patients who got infected before vaccination. Additionally, factors associated with COVID-19 unfavorable outcome were assessed.

Methods: Adult patients with RD who have been vaccinated for SARS-CoV-2 were consecutively included between June 1st and December 21st, 2021. Confirmed SARS-CoV-2 infection (RT-PCR o serology) was reported by the treated physician. Infection after an incomplete scheme was defined when the event was diagnosed at least 14 days after first dose; and after a complete scheme when it occurred > 14 days after second dose. Homologous scheme is defined by two same doses of vaccine and heterologous by two different doses. Patients with previous SARS-CoV-2 infection were excluded. To compare SARS-CoV-2 infection characteristics in not vaccinated patients, subjects from the SAR-COVID registry, which includes patients with RD and SARS-CoV-2 infection, were matched 2:1 by gender, age and RD.

WHO-Ordinal Scale ≥5 was used to define unfavorable infection outcome. Descriptive statics, Chi2 test, Fischer test, T test and ANOVA were used.

Results: A total of 1350 patients from the SAR COVAC registry were included, 67 (5%) presented SARS-CoV-2 infection after vaccination. The later were mostly (72%) females with a mean age of 57 (SD 15) years old. The most frequent RD were rheumatoid arthritis (41%), psoriatic arthritis (12%) and systemic lupus erythematosus (10%). At vaccination, most of them (75%) had low disease activity or remission, 19% were taking steroids, 39% methotrexate, 27% bDMARDs and 6% JAK inhibitors.

A total of 11 (16%) patients had SARS-CoV-2 infection <14 days after the first vaccine dose, 39 (58%) after an incomplete scheme and 17 (25 %) following a complete one. In the incomplete scheme group, 59% received Gam-COVID-Vac, 31% ChAdOx1 nCov-19 and 10% BBIBP-CorV; and in patients with complete scheme 47%, 24% and 29%, respectively. No event was reported after a complete heterologous scheme. No significant differences regarding sociodemoghraphic characteristics, RD, disease treatment, type of vaccine and regimen was found between in those with infection and those without it.

After vaccination only 8 (12%) of the patients who got infected had an unfavorable course, 88% of them following an incomplete scheme (5 received Gam-COVID-Vac, 1 ChAdOx1 nCov-19 and 1 BBIBP-CorV) and one subject after a complete homologous Gam-COVID-Vac scheme. Having an unfavorable outcome of SARS-CoV-2 infection was associated to: male gender [63% vs 24%, p=0.036], older age [mean 70 years (SD 7) vs 55 years (SD 15), p=0.005], being Caucasian [100% vs 54%, p=0.018], higher education [mean 17 years (SD 4) vs 12 years (SD 4), p=0.010], the presence of comorbidities [100% vs 39%, p=0.001, having pulmonary disease [37% vs 5%, p=0.019], dyslipidemia [63% vs 17%, p=0.011] and arterial hypertension [63% vs 24%, p=0.036], RD, treatments, disease activity and types of vaccines received were comparable between groups.

When comparing patients with and without vaccination prior SARS-CoV-2 infection, those who received at least one dose of vaccine had less frequently severe COVID-19 (12% vs 24%, p=0.067) and presented lower mortality due to COVID-19 (3% vs 6%, p=0.498). However these differences did not reach statistical significance.

Conclusion: In the SAR-CoVAC registry 5% of the patients had SARS-CoV-2 infection after vaccination, most of them mild and 25% after a complete scheme. Any vaccine was associated with severe COVID-19. When comparing with non-vaccinated patients, those with at least one dose, had less frequently severe disease and died due COVID-19.

Disclosure of Interests: None declared