Uptake, safety, and effectiveness of inactivated influenza vaccine in patients with inflammatory bowel disease: a nationwide study in the UK using data from the Clinical Practice Research Datalink.

ObjectiveWe investigated UK wide inactivated influenza vaccine (IIV) uptake in adults with inflammatory bowel disease (IBD), the association between vaccination against influenza and IBD flare, and the effectiveness of IIV in preventing morbidity and mortality. DesignData for adults with IBD prior to 1st September 2018 were extracted from the Clinical Practice Research Datalink (CPRD) Gold, a database of electronic health records originated during routine care of patients in the UK. It is linked to hospitalization and mortality records. We calculated the proportion of patients vaccinated against seasonal influenza in the 2018-2019 influenza cycle. To investigate vaccine effectiveness, we calculated propensity score (PS) for vaccination and undertook Cox proportional hazard regression with inverse-probability treatment weighting on PS. We employed self-controlled case series (SCCS) to investigate the association between vaccination and IBD flare. ResultsData for 13,631 IBD patients (50.4% male, mean age 52.9 years) were included. Fifty percent were vaccinated during the influenza cycle while 32.1% were vaccinated before influenza virus circulated in the community. Vaccination was associated with a non-significant reduction in hospitalisation for pneumonia (aHR (95%CI) 0.52 (0.20-1.37), including in the influenza active period (aHR (95%CI) 0.48 (0.18-1.27)). Administration of the influenza vaccine was not associated with IBD flare. ConclusionThe uptake of influenza vaccine is low in IBD patients and the majority are not vaccinated before influenza virus circulates in the community. Vaccination with the IIV is not associated with IBD flare. These findings add to the evidence to promote vaccination in patients with IBD. Key messagesO_ST_ABSWhat is already known on the topicC_ST_ABSO_LIInactivated influenza vaccine is recommended in people with IBD treated with immune suppressing drugs. C_LIO_LIConcerns about influenza vaccine causing IBD flare and lack of data on the effectiveness of influenza vaccine in people with IBD are barriers to seasonal influenza vaccination in this population. C_LI What this study addsO_LIThe uptake of seasonal influenza vaccination is low in IBD patients. C_LIO_LISeasonal influenza vaccination is not associated with IBD flare and is more likely to prevent serious complications of influenza in this population. C_LI How this study might affect research, practice, or policyO_LIThis study provides new data on the uptake, effectiveness, and safety of influenza vaccine in people with IBD and adds to the accumulating evidence to promote vaccination in this population. C_LI