Overview
Previous population-based studies have examined the association between certain skin conditions and the COVID-19 vaccine, e.g., bullous pemphigoid (BP) - a rare blistering disease; shingles - a painful and disabling condition; and urticaria, i.e., hives - a painful swelling condition. However, these studies showed conflicting results due to limitations, such as study populations not being representative of their target general population.
We used routinely collected patient data from over 2,000 general practices across the UK from the Clinical Practice Research Datalink (CPRD). The databases offered by CPRD (GOLD and Aurum) allowed us to research rare diseases like bullous pemphigoid, run analyses with study populations representative of the UK population, and consider all vaccine products administered in the UK.
This project aimed to determine if there is any association between COVID-19 vaccines, bullous pemphigoid, shingles, and hives. By providing accurate estimates of the risk of developing said conditions, we aimed to increase awareness of the potential side effects of the COVID-19 vaccines and which vaccine type may have a higher risk.
Key facts
1. Why do the research?
Given vaccine hesitancy, this study may reassure patients that there is no association between the vaccines and skin conditions and encourage people to have/continue taking the vaccine, protecting themselves and others. If an association is found, patients can make a more informed decision than they currently are making and be aware of which type of vaccine has fewer side-effects.
2. How was the research conducted?
The research was divided into three parts:
Study 1 examined the effect of the COVID-19 vaccine programme on the incidence of BP, shingles, and hives using a retrospective cohort study design. We determined how the incidence of the investigated skin conditions changed following the programme's start (01/2021-05/2023) compared to the period before the programme (01/2019-12/2020).
Study 2 examined the association between COVID-19 vaccines and BP. We used a nested case-control design to estimate the BP risk following COVID-19 vaccines, as it is a rare disease. We also estimated BP risk following the number of doses, vaccine products, and vaccine technologies (e.g., mRNA vaccine).
Study 3 examined the association between COVID-19 vaccines, shingles and hives. We have treated each patient as their own control (self-controlled case series study) to estimate the risk of the examined conditions. The advantage of this approach was that we did not have to account for factors influencing vaccine use and the risk of shingles and hives. This study also looked at different doses, vaccine products, and technologies.
3. What do the results mean for patients?
The findings of the study are currently being written up and we hope to publish soon.
Who funded the study?
This project was funded by the National Institute for Health and Care School for Primary Care Research.