Another study evaluating the efficacy of mRNA vaccines against infection in a Veterans Affairs cohort of 14,697 IBD patients in the US (20% were taking TNF inhibitors) found that full vaccination status reduced the risk of infection by 69%, showing that the effectiveness of a two-dose course of an mRNA vaccine was 80.4% in this cohort, which is lower to the efficacy reported in the registration trials [181]. Here, TNF is linked to inflammatory bowel disease.