Due to the rapid development of the COVID-19 pandemic, vaccines were developed to slow down the infection rate. The effectiveness of the vaccines has been shown, but studies are needed to monitor the safety of COVID-19 vaccines, and several associated adverse events such as herpes zoster and Bell’s palsy have been reported.
Herpes zoster is a painful skin rash that can affects the nervous system. About 20% of the cases may experience prolonged pain, and more rarely life-threatening complications may occur in around 2% of the cases. Bell’s palsy, an unexplained facial muscle weakness, may lead to incomplete eye closure that can potentially affect daily life.
Studies evaluating the risk of herpes zoster and Bell’s palsy after COVID-19 vaccination reported controversial results because the size of those studies were often small. Given around 2,500 and 1,000 cases of herpes zoster and Bell’s palsy were reported in the UK after mass vaccination, we plan to investigate the risk of herpes zoster and Bell’s palsy and exam the patient characteristics related to the events following COVID-19 vaccination. Using a large healthcare database, this study could provide more comprehensive knowledge of herpes zoster and Bell’s palsy after COVID-19 vaccination.
The safety of COVID-19 vaccine remains a major public health interest since their approval for emergency use. Due to time constraints to bring these novel entities into the market, limited pharmacovigilance data have been generated through clinical trials. Hence, several adverse events such as herpes zoster and Bell’s palsy associated with COVID-19 vaccines remained uncertain. This study aims to investigate the risk of herpes zoster and Bell’s palsy following COVID-19 vaccination.
This Self-controlled case series (SCCS) study will use CPRD Aurum from December 2020 to April 2021. Patients aged 16 or above, receiving at least one dose of COVID-19 vaccination, and have their first diagnosis of herpes zoster or Bell’s palsy between 8 December 2020 and 30 April 2021 will be included. The exposure periods will be defined as 0-13 days and 14-27 days on or after first and second dose of vaccination, while all the other periods will be defined as baseline periods. Conditional poisson regression will be applied to estimate the adjusted incidence rate ratio (aIRR) and its 95% confidence interval. The aIRR of herpes zoster and Bell’s palsy will be estimated in patients with different characteristics to identify the potential effect modifiers. A nested case-control study will also be conducted and treated as a confirmatory analysis. Each case of herpes zoster or Bell’s palsy will be matched to 10 controls by sex, age, Charlson comorbidity index and date of attendance. Conditional logistic regression will be applied for the confirmatory analysis with adjustment for patient characteristics.
Given the high number of herpes zoster and Bell’s palsy after COVID-19 vaccination were reported by the Medicines and Healthcare products Regulatory Agency, this study could inform further rollout of vaccination program.
• Herpes zoster
• Bell’s palsy
Darren Ashcroft - Chief Investigator - University of Manchester
Teng-Chou Chen - Corresponding Applicant - University of Manchester
Ian Wong - Collaborator - University College London ( UCL )
Matthew Carr - Collaborator - University of Manchester
Patient Level Index of Multiple Deprivation;Practice Level Index of Multiple Deprivation