Bell’s palsy is the sudden onset of unilateral facial palsy, and in the majority of cases (70%) the disease resolves within six months without treatment.
The chances of recovery are even higher (90%) if patients receive early treatment with corticosteroids.
Research suggests that a small number of cases have been reported in clinical trials of Covid-19 mRNA vaccines, but the association’s analyzes have reached conflicting conclusions.
In the United States, the Federal Drug Administration (FDA) did not consider that there was a clear causal association for the two mRNA vaccines – the Pfizer / BioNTech (BNT162b2) and Moderna (mRNA-1273) vaccines.
Acute partial facial paralysis has been reported by the European Medicines Agency as a rare side effect of the two vaccines, which are used in the UK.
In new research published in The Lancet Infectious Diseases Journal, the researchers analyzed cases of illness linked to two vaccines approved in Hong Kong – CoronaVac and the Pfizer vaccine.
Bell’s palsy cases were included in the analysis if they occurred within 42 days of a first or second dose of vaccine, within the time frame of the study.
Between February 23 and May 4 of this year, 28 clinically confirmed cases of Bell’s palsy were identified among the 451,939 people who received at least a first dose of CoronaVac.
Sixteen cases were identified among the 537,205 individuals who received at least a first dose of Pfizer vaccine.
Experts analyzed data from 2010 to 20 and estimated the background risk of Bell’s palsy in Hong Kong – around 27 cases per 100,000 people per year.
Global estimates range from 15 to 30 cases.
The study found that receiving CoronaVac was associated with a 2.4-fold increased risk of Bell’s palsy, while the Pfizer vaccine was not associated with a significantly increased risk.
The researchers concluded that for every 100,000 people vaccinated with CoronaVac, an additional 4.8 people can develop Bell’s palsy.
For the Pfizer / BioNTech jab, the increased risk was equivalent to two more cases per 100,000 people, which can be attributed to underpower in the current study.
Lead author Professor Ian Chi Kei Wong, University of Hong Kong, said: “Our study suggests a slight increased risk of Bell’s palsy associated with CoronaVac vaccination.
“Nevertheless, Bell’s palsy remains a rare, mostly temporary, adverse event.
“All the evidence to date, from several studies, shows that the beneficial and protective effects of the inactivated Covid-19 vaccine far outweigh the risks. “
Additional reports by the PA