P107 Association between the COVID-19 vaccination programme and incidence rates of bullous pemphigoid, herpes zoster and urticaria in the UK: an interrupted time series analysis

Abstract Following the introduction of the COVID-19 vaccination programme, there were numerous reports of adverse cutaneous reactions. In particular, several population-based studies reported associations between the COVID-19 vaccines and bullous pemphigoid (BP), herpes zoster (HZ) and urticaria. However, these studies were hospital based and not representative of the UK population. Reliable estimates of the risks of these serious conditions following vaccination may help patients make informed decisions. We aimed to compare monthly incidence rates (IRs) of BP, HZ and urticaria before and after the UK’s COVID-19 programme started. We conducted a population-based cohort study using the Clinical Practice Research Datalink (during 1 January 2019 to 31 May 2023). We estimated monthly IRs (cases per 100 000 person-years) of the examined conditions. We used interrupted time series analysis to compare changes in slopes (i.e. trajectories) of examined IRs before and after intervention (vaccine programme). Sensitivity analyses accounted for COVID-19 national lockdowns and the total number of general practitioner appointments. There were 3506 incident cases of BP, 129 668 of HZ, 63 320 of urticaria and 29 623 of venous leg ulcer during the observation period. The median ages (in years) were 80 (interquartile range 71–86) for patients with BP, 61 (47–72) for HZ and 45 (32–61) for urticaria. The analysis did not detect changes in IRs of BP postintervention. Furthermore, no pre- or postintervention slopes were detected. There was a downward preintervention slope for the IR of HZ [IR −4.44, 95% confidence interval (CI) −5.54 to −3.35; P < 0.005]. The IR for HZ increased postintervention compared with the preintervention period (5.15, 95% CI 3.43–6.88; P < 0.005). However, we could not detect a slope postintervention. Sensitivity analysis results were similar. There was a downward preintervention slope for the IR of urticaria (−3.42, 95% CI −4.13 to −2.70; P < 0.005). The urticaria IR increased postintervention compared with the preintervention period (4.40, 95% CI 3.27–5.53; P < 0.005), resulting in an upward slope (0.98, 95% CI 0.43–1.52; P < 0.005). However, we could not detect a slope postintervention after accounting for lockdowns or the number of general practitioner appointments. In conclusion, we did not find a link between vaccinations and BP. There were modest increases in IRs for HZ and urticaria, which could be explained by COVID-19 vaccines. However, for many patients, the benefits of vaccination will likely outweigh the potential risks of HZ and urticaria. Further studies to estimate outcome risk based on individual patient-level data (e.g. case–control and self-controlled case series designs) should be used to determine whether the reported increases in HZ and urticaria IRs were driven by vaccinations or other coincident factors.