A large South Korean study found a small but significant increase in cases of facial paralysis within 28 days after receiving a COVID-19 vaccine, highlighting the need for post-vaccination monitoring. Ta.
Study: Risk of facial paralysis after COVID-19 vaccination, South Korea, 2021-2022. Image credit: sruilk/Shutterstock.com
A recent study published in Emerging infection reports on a potential association between vaccination against coronavirus disease 2019 (COVID-19) and facial paralysis (FP). Researchers found that the risk of FP increased within 28 days after vaccination, particularly after the first and second doses of both messenger ribonucleic acid (mRNA) and viral vaccines.
background
Vaccines were rapidly distributed during the COVID-19 pandemic, raising concerns about potential side effects, including FP. Although clinical trials did not raise any major safety issues, a disparity in FP cases was observed in vaccinated people compared to the general population.
FP, characterized by sudden facial paralysis, is thought to be associated with infections, autoimmune reactions, and vaccination. It was then prioritized as an adverse event by the Emergency Vaccine Safety Platform (SPEAC). Several studies have investigated the association between COVID-19 vaccines and FP, but the results have been inconsistent.
Differences in study population size, ethnicity, vaccine type, dose, and statistical methods may explain the variation in results. Even systematic reviews and meta-analyses of these studies could not fully resolve the issue due to limited inclusion criteria.
These inconsistent findings highlight the need for more robust and larger studies to reach a clear consensus on the safety of COVID-19 vaccines regarding FP. In this study, researchers conducted a self-controlled case series (SCCS) analysis to assess the potential association between FP and COVID-19 vaccines.
About research
This study was conducted as part of Korea’s COVID-19 Vaccine Safety Study Committee (CoVaSC). Researchers used two large-scale databases, the COVID-19 Vaccination Registry and National Health Insurance Service (NHIS) claims data, to investigate the spread of COVID-19 infections from February 2021 to March 2022. We identified individuals aged 18 years and older who had received an infectious disease vaccination.
Those with missing vaccination information or a previous FP diagnosis were excluded. Vaccines were classified into the following types: mRNA vaccines (BNT162b2 and mRNA-1273), viral vector vaccines (ChAdOx1 nCoV-19 and Ad26.COV2.S), and recombinant protein vaccines (NVX-CoV2373).
An SCCS design was adopted to compare FP incidence during a 28-day post-vaccination risk window with a control window. Factors such as age, gender, comorbidities, and insurance were considered. The primary outcome was prescription of oral or parenteral corticosteroids on the same day as diagnosis of FP. This study aimed to investigate vaccine types, doses, and homologous or heterogeneous vaccination regimens.
Statistical analyzes included the use of t-tests, chi-square tests, conditional Poisson regression, incidence rate ratios (IRR), subgroup analysis, and Benjamini-Hochberg adjustment. Subgroup and sensitivity analyzes were also conducted to ensure robustness.
Results and discussion
During the study period, 129,956,027 doses of the COVID-19 vaccine were administered to 44,564,345 people in South Korea, resulting in 15,742 FP patients prescribed corticosteroids. Of these, 5,211 FP cases occurred within 1 to 28 days after vaccination, resulting in an incidence of 4.0 FP cases per million vaccinations.
Overall FP risk increased within the first 28 days after vaccination (IRR 1.12). An increased risk was observed after the second dose (IRR 1.07) and when the first and second doses were combined (IRR 1.08), but an increased risk was observed after the third dose (IRR 1.01). No increase was observed.
Both homologous and heterologous vaccination showed an increased risk of FP (IRR 1.14 and 1.08, respectively). The IRR for mRNA vaccines was 1.11, whereas the risk for viral vector vaccines was higher (IRR 1.37). Sensitivity analyzes confirmed that these results were robust across different risk windows and when excluding COVID-19.
The real-world evidence provided in this study is consistent with previous research linking FP to COVID-19 vaccination.
The current large-scale study addresses several inconsistencies with previous studies, including possible misclassification of FP cases due to reliance on International Classification of Diseases, 10th Revision codes, and discrepancies in timing of occurrence and diagnosis. , and the potential for residual confounding of occurrence and diagnosis. Undiagnosed new coronavirus infection.
conclusion
In conclusion, this study found a transient increase in the risk of FP after administration of a COVID-19 vaccine, regardless of vaccine type or dose.
However, this risk does not preclude vaccination, as the actual number of cases is small and FP is usually mild and manageable. Physicians are encouraged to monitor for neurological signs after vaccination and discuss the risk-benefit profile of COVID-19 vaccines with patients.
