OBJECTIVE: the recommendations of the Spanish Ministry of Health on vaccination in risk groups include mesalazine among the treatments with a possible negative effect on its effectiveness. However, this is not the recommendation of most experts. Our objective was to evaluate the effect of mesalazine on the humoral response to the SARS-CoV-2 vaccine in patients with inflammatory bowel disease (IBD). METHODS: VACOVEII is a Spanish, prospective, multicenter study promoted by GETECCU, which evaluates the effectiveness of the SARS-CoV-2 vaccine in patients with IBD. This study includes IBD patients who have recieved the full vaccination schedule and without previous COVID-19 infection. Seroconversion was set at 260 BAU/mL (centralized determination) and was assessed 6 months after full vaccination. In this subanalysis of the study, we compare the effectivenes of the vaccine between patients treated with mesalazine and patients without treatment. RESULTS: A total of 124 patients without immunosuppressive therapy were included, of which 32 did not receive any treatment and 92 received only mesalazine. Six months after full vaccination, no significant differences are observed in the mean concentrations of IgG anti-S between both groups. In the multivariate analysis, antibody titers were independently associated with the use of mRNA vaccines and with SARS-CoV-2 infection. CONCLUSION: Mesalazine does not have a negative effect on the response to SARS-CoV-2 vaccines in IBD patients.
