P108 Association between COVID-19 vaccines and bullous pemphigoid: a UK population-based study

Abstract Bullous pemphigoid (BP) is an autoimmune blistering skin disease common in older people. BP has previously been reported following COVID-19 vaccines, but the only population-based study to date showed no association between COVID-19 vaccines and BP. However, the study population was hospital based, which represents a more severely affected subgroup of the whole population. Accurately estimating BP risk following COVID-19 vaccines using a representative population can help clinicians, other healthcare professionals and patients make informed decisions regarding vaccinations. We have addressed this research gap by conducting a population-based nested case–control study to estimate BP risk following COVID-19 vaccines. We used the Clinical Practice Research Datalink (covering > 2000 general practices) to identify cases of BP between 2021 and 2023. Patients were matched by age, sex and general practice with up to four controls. We used conditional logistic regression to estimate adjusted odds ratios (aORs) of developing BP following COVID-19 vaccines within 3 months before the diagnosis and the number of doses (0, 1, 2, ≥ 3) preceding the diagnosis. aORs were estimated for the general association between COVID-19 vaccines and BP; for products: the AstraZeneca, Pfizer and Spikevax vaccines; and for vaccine types: mRNA or vector. We adjusted a priori for stroke, dementia and Parkinson disease. The multivariable analysis additionally adjusted for the latest gliptins, antiepileptic prescriptions issued within 1 year before BP diagnosis, and anti-inflammatory drugs (within 3 months). Subgroup analysis by the Charlson Comorbidity Index (CCI: 0–2, ≥ 3) was used to explore the risks and benefits of the vaccine in groups with varying risks for post-COVID-19 complications. We conducted a sensitivity analysis that adjusted for ethnicity and deprivation to account for sociodemographic inequalities in vaccination uptake. Our study population had 2828 cases of BP and 11 067 controls (median age 80 years, interquartile range 72–86; 50.5% female). We found no associations between vaccines (general, products, types) and BP risk. We found a reduced risk of BP following at least three vaccine doses compared with no vaccine doses (aOR 0.48, 95% confidence interval 0.29–0.79; P < 0.005). The results were similar in the CCI subgroup analysis. After accounting for vaccine uptake inequalities, no association between vaccines, doses and BP was found. In conclusion, we did not find evidence of COVID-19 vaccines leading to an onset of BP. Our finding of a potential protective effect with three or more doses may reassure clinicians and people currently eligible to consider COVID-19 vaccination, and in particular provide evidence to discuss risks and benefits with vaccine-hesitant patients at risk of BP when considering COVID-19 vaccination.