Four trialists for Pfizer-BioNTech's vaccine suffered temporary facial paralysis after taking the drug, according to US drugs regulator the Federal Drugs Agency (FDA).
Despite this being ‘consistent with the expected background rate in the general population’ and there being no evidence that the condition, Bell’s palsy, is a side effect of the drug, the agency has recommended ‘surveillance for cases of Bell’s palsy with deployment of the vaccine into larger populations.’
Bell’s palsy usually sees one side of the face paralysed with the other drooping as muscles loosen. It’s unclear what causes the condition and the temporary paralysis usually goes away on its own.
According to the FDA's analysis, side effects are common but apparently minor, with 84 percent reporting some kind of reaction, such as fatigue or headaches.
Other than that, the vaccine appears to have received good marks, with the FDA finding that even just the first jab of the two-dose vaccine is about 50 percent effective and also reduces the risk of severe Covid-19 symptoms.
On Tuesday, the UK became the first country in the world to begin administering the vaccine to its general population.