Risk of Facial Paralysis Extremely Low With COVID-19 Vaccines
Partly because of social media and messaging from vigilant anti-vaccination groups, any safety signal with the COVID-19 vaccine is overplayed. One of those is facial paralysis, which was investigated in a new study. Find out why French researchers say the side effect is extremely rare with COVID-19 vaccines and even less common than with other viral vaccines.
GRENOBLE, FRANCE – After a few cases of facial paralysis were identified in phase 3 clinical trials of mRNA COVID-19 vaccines, questions arose about whether the side effect was some type of safety signal. A new study finds, however, that the risk is very low, if it exists at all, and is no greater than with a range of viral vaccinations for other conditions.
A research letter in JAMA Internal Medicine describes how several cases of facial paralysis were observed in vaccine groups -- 7 of 35 654 -- compared with 1 case among the 35,611 who received placebo.
https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2779389?guestAccessKey=0b6ec8d9-1e74-4ea3-baac-f8b929de87ec&utm_source=silverchair&utm_medium=email&utm_campaign=article_alert-jamainternalmedicine&utm_term=mostread&utm_content=olf-widget_05162021
The authors from University Grenoble Alpes and Grenoble Alpes University Hospital note that no causal relationship was established from clinical trials. Still, the U.S. Food and Drug Administration recommended monitoring vaccine recipients for facial paralysis. Researchers sought to look more closely at the possible safety signal using the World Health Organization pharmacovigilance database, VigiBase.
The article explains that disproportionality analyses are “hypothesis-generating methods that aim to detect putative associations between drugs and adverse drug reactions. Such methods quantify the extent to which a drug–event combination occurs disproportionally compared with what would be expected in the absence of any association, but they do not provide risk quantification because the population actually exposed to the drugs is unknown.”
Four analyses with two control groups – one involving all other viral vaccines and the other restricted to influenza vaccines -- and 2 facial paralysis definitions -- broad and narrow – were performed.
Among the 133 883 cases of adverse drug reactions reported with mRNA COVID-19 vaccines in the World Health Organization pharmacovigilance database by March 9, the study team identified 844 (0.6%) facial paralysis-related events, including 683 cases of facial paralysis, 168 cases of facial paresis, 25 cases of facial spasms, and 13 cases of facial nerve disorders, with some adverse events co-reported in the same case.
Of those, 749 cases were reported with the Pfizer-BioNTech vaccine, and 95 cases were reported with the Moderna vaccine. Most of the patients, 57, were female (67.8%), and the median (interquartile range) age was 49 (39-63) years. The side effect occurred after a median (range) time of 2 (0-79) days, according to the report.
At the same time, researchers identified 5734 (0.5%) and 2087 (0.7%) cases of facial paralysis among the about 1.3 million cases of adverse drug reactions reported with other viral vaccines, and the 314, 980 cases reported with influenza vaccines, respectively.
No signal of disproportionality of facial paralysis for broad and narrow definitions vs other viral vaccines (IC025 = −0.01 and IC025 = −0.06) or influenza vaccines alone (IC025 = −1.36 and IC025 = −0.32) was detected, the authors advise.
The article describes how facial paralysis can be observed with many conditions, including viral infections, traumatic injury, cancers or hormonal changes during pregnancy. Researchers write that idiopathic causes, essentially Bell palsy, are “unilateral, generally reverse spontaneously, and cause partial or complete acute weaknesses of the face,” it adds.
The issue is in no way unique to COVID-19 vaccines, the authors point out, explaining, “Isolated facial paralysis after vaccination has been reported as case reports for decades with almost all viral vaccines, and it is thought to be immune-mediated or induced by viral reactivations (e.g, reactivation of a herpes virus infection). However, to date, pharmacoepidemiological studies have failed to identify a higher risk of facial paralysis after vaccination.”
Yet, they emphasize that, compared with other viral vaccines, mRNA COVID-19 vaccines did not display a signal of facial paralysis. “Therefore, despite selective reporting and a potential delay in reporting and transferring cases among pharmacovigilance databases, the reporting rate of facial paralysis after mRNA COVID-19 vaccination found in the present study is not higher than that observed with other viral vaccines. Although we adjusted for sex and age, residual confounding and reporting bias may influence the results. To conclude, if an association between facial paralysis and mRNA COVID-19 vaccines exists, the risk is likely very low, as with other viral vaccines.”
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