While an association was found, the adverse events are very rare.
A recent study conducted by investigators from the Centre for Safe Medication Practice and Research at the University of Hong Kong, in collaboration with the School of Nursing, has found that there is an increased risk of Bell’s Palsy after the administration of the CoronaVac COVID-19 vaccine.
“Bell's palsy is usually transient, with 70% of patients recovering within 6 months without treatment,” the authors wrote. “However, patients with incomplete recovery of facial function might have incomplete eye closure, brow ptosis, and nasal valve collapse, which can potentially affect daily life.”
For the study, the team of investigators conducted a nested case-control study where they assessed the risk of Bell’s Palsy within 42 days after the administration of either the Pfizer or CoronaVac COVID-19 vaccines.
The study included participants who received a first dose of either vaccine between February and May of 2021 and were matched 1:4 by age, sex, admission setting and admission date.
Findings from the study showed that 451,939 received 1 dose of CoronaVac and 537,205 received 1 dose of Pfizer. Of those, there were 28 clinically confirmed cases of Bell’s Palsy reported following the CoronaVac vaccine and 16 following the Pfizer vaccine.
Additional findings demonstrated that the nested case-control analysis showed 298 cases which were matched to 1181 controls, and the adjusted odds ratio were 2.385 for CoronaVac and 1.755 Pfizer.
“Our findings suggest an overall increased risk of Bell's palsy after CoronaVac vaccination,” the authors wrote. “However, the beneficial and protective effects of the inactivated COVID-19 vaccine far outweigh the risk of this generally self-limiting adverse event. Additional studies are needed in other regions to confirm our findings.”