Peripheral facial palsy (PFP) is a rare adverse reaction identified from clinical trials of coronavirus disease 2019 (COVID-19) vaccines (messenger ribonucleic acid [mRNA] and viral vector). Few data are available on their onset patterns and risk of recurrence after re- injection of a COVID-19 vaccine, the objective of this study was to describe PFP cases attributed to COVID-19 vaccines.

All cases of facial paralysis reported to the Regional Pharmacovigilance Center of Centre-Val de Loire area between January and October 2021, in which the role of a COVID-19 vaccine was suspected, were selected. Based on initial data and following additional information requested, each case was reviewed and analyzed to include only confirmed cases of PFP for which the role of the vaccine could be retained. From the 38 cases reported, 23 were included (15 excluded because of diagnosis not retained). They occurred in 12 men and 11 women (median age of 51 years). The first clinical manifestations occurred with a median time of 9 days after COVID-19 vaccine injection, and the paralysis was homolateral to the vaccinated arm in 70%. The etiological workup, always negative, included brain imaging (48%), infectious serologies (74%) and Covid-19 PCR (52%). Corticosteroid therapy was prescribed for 20 (87%) patients, combined with aciclovir in 12 (52%). At 4-month follow-up, clinical manifestations had regressed completely or partially in 20 (87%) of the 23 patients (median time of 30 days). From them 12 (60%) received another dose of COVID-19 vaccine and none had a recurrence and the PFP regressed despite the second dose in 2 of the 3 patients not fully recovered at 4 months.

The potential mechanism of PFP after COVID-19 vaccine, which don't have a specific profile, is probably the interferon-γ. Moreover, the risk of recurrence after a new injection appears to be very low, which makes it possible to continue the vaccination.