A booster dose of SARS-COV-2 vaccine improves suboptimal seroconversion rates in patients with inflammatory bowel disease. Results of a prospective multicenter study of GETECCU (VACOVEII study).

Background: The response to SARS-CoV-2 vaccination decreases in inflammatory bowel disease (IBD) patients, specially under anti-TNF treatment. However, data on medium-term effectiveness are limited, specially using new recommended seroconversion rate (>260BAU/mL). Our aim was to evaluate the 6-month>260 BAU-seroconversion rate after full vaccination and after booster-dose.
Methods: VACOVEII is a Spanish multicenter, prospective study promoted by GETECCU. IBD patients full vaccinated against SARS-CoV-2 and without previous COVID-19 infection, treated or not with immunosuppressants, were included. The booster dose was administered 6 months after the full vaccination. Seroconversion was set at 260BAU/mL, according to most recent recommendations and was assessed 6 months after the full vaccination and 6 months after booster-dose.
Results: Between October 2021 and March 2022, 313 patients were included (124 no treatment or mesalazine; 55 immunomodulators; 87 anti-TNF; 19 anti-integrin; and 28 ustekinumab). Most patients received mRNA-vaccines (86%). Six months after full vaccination, overall seroconversion rate was 44.1%, being significantly lower among patients on anti-TNF (19.5%, p<0.001) and ustekinumab (35.7%, p=0.031). The seroconversion rate after booster was 92%. Again, anti-TNF patients had a significantly lower seroconversion rate (67%, p<0.001). mRNA-vaccine improved seroconversion rate (OR 11.720 [95% CI 2.26-60.512]).
Conclusion: The full vaccination regimen achieves suboptimal response in IBD patients, specially among those anti-TNF or ustekinumab. The booster dose improves seroconversion rate in all patients, although it remains limited in those treated with anti-TNF. These results reinforce the need to prioritize future booster doses in patients on immunosuppressants therapy, specially under anti-TNF, and using mRNA-vaccines.
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