COVID-19 Vaccine Side Effect Facial Paralysis?..."Unvaccinated Infected Individuals Have 84% Higher Risk"

Seoul National University Hospital Announces Follow-up Results Based on COVID-19 Data Tracking

A study has found that individuals who have not completed their second dose of the vaccine or who experience severe COVID-19 infection have a higher risk of developing facial paralysis compared to those who do not.

Receiving a COVID-19 vaccine booster shot./Photo by Hyunmin Kim kimhyun81@

Professor Sangmin Park's team from the Department of Family Medicine at Seoul National University Hospital (researcher Hyejun Kim, Professor Seoksong Jeong from the Department of Information Science at CHA University) announced on the 11th the results of an analysis on the risk of facial paralysis caused by infection with the COVID-19 (SARS-CoV-2) virus, based on data from 48,158,464 individuals registered with the National Health Insurance Service and the Korea Disease Control and Prevention Agency.

Facial paralysis is a condition in which the muscles responsible for facial expressions and movements become paralyzed due to abnormalities in the facial nerve function. It occurs due to acquired causes such as inflammation or trauma.

Previous studies on COVID-19 and facial paralysis have suggested that neurological sequelae can appear up to 12 months after COVID-19 infection, and that facial paralysis can occur as a side effect of vaccination. However, most existing studies have focused on vaccine side effects, and follow-up observations of facial paralysis symptoms were conducted only for a short period. Therefore, it was difficult to clearly define the risk of facial paralysis caused by COVID-19 infection itself and the risk of delayed onset facial paralysis after infection.

Risk of facial paralysis according to vaccination status and COVID-19 severity.
[Image provided by Seoul National University Hospital]

To evaluate this, the research team divided subjects into an infected group (11,593,365 people) and a non-infected group (36,565,099 people) based on COVID-19 infection status and conducted follow-up observations for up to four months. The results showed that the risk of facial paralysis was 24% higher in the COVID-19 infected group compared to the non-infected group.

When classified based on vaccination completion status, among those who had not completed vaccination (unvaccinated or only first dose), the risk of facial paralysis in the infected group was 84% higher than in the non-infected group. In contrast, among those who had completed vaccination (second dose), the risk of facial paralysis in the infected group was 20% higher than in the non-infected group.

Furthermore, in both vaccinated and unvaccinated groups, the more severe the COVID-19 symptoms, the higher the risk of facial paralysis. In particular, individuals with moderate to severe symptoms after infection had more than twice the risk of facial paralysis compared to non-infected individuals. Among those with a history of facial paralysis prior to follow-up, there was a tendency for increased risk of recurrence of facial paralysis due to COVID-19 infection in cases where the COVID-19 vaccine was not administered or only the first dose was given.

Professor Park stated, "These study results indicate that unvaccinated individuals or those who have only received the first dose should be more cautious about facial paralysis symptoms when infected with COVID-19," and added, "Further follow-up studies are needed to gain a more comprehensive understanding and clarify the mechanisms underlying the association between COVID-19 and facial paralysis."

Meanwhile, this study was published in the latest issue of the international infectious disease journal Clinical Microbiology and Infection.

Professor Sangmin Park, Department of Family Medicine, Seoul National University Hospital; Researcher Hyejun Kim, Seoul National University College of Medicine; Professor Seoksong Jeong. (from left)
[Photo by Seoul National University Hospital]

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