[Acute facial paresis as a possible complication of vaccination against SARS-CoV-2]

Observed-over-Expected analysis as additional method for pharmacovigilance signal detection in large-scaled spontaneous adverse event reporting

BACKGROUND

The large-scale COVID-19 vaccination campaigns in 2021 and 2022 led to a rapid increase in numbers of received adverse event reports in spontaneous reporting systems. As background incidences of naturally occurring medical events became increasingly relevant for causality assessment of potential associations with the vaccines, a novel approach for signal detection was warranted.

OBJECTIVES

This article illustrates the Observed-over-Expected (O/E) analysis as an additional method for signal detection and risk assessment in large-scaled spontaneous reporting systems.

METHODS

All individual case safety reports (ICSRs) concerning idiopathic peripheral facial paralysis or Bell's palsy following administration of the COVID-19 vaccines (n = 291) manufactured by Pfizer/BioNTech (Comirnaty), Moderna (Spikevax), AstraZeneca (Vaxzevria) and Janssen (JCOVDEN) received by the National Pharmacovigilance Centre Lareb until 24th March 2022 were included in the O/E analysis, within a risk window of 7 and 14 days following immunisation. Dutch background incidence rates from 2019 and exposure of the Dutch population to the vaccines were obtained from the PHARMO institute and RIVM. The data was stratified in age groups, gender and administered dose in order to differentiate between population subgroups.

RESULTS

Bell's palsy was reported more frequently than expected in several population subgroups following administration of all four COVID-19 vaccines, including children and adolescents. Among children, a high O/E ratio was found for boys aged 5-14 years after receiving the Pfizer/BioNTech vaccine. Regarding adolescents and young adults, women aged 15-24 years receiving Pfizer/BioNTech and Moderna, and men aged 15-24 years receiving Janssen developed Bell's palsy more often than expected. Furthermore, O/E ratios were high for individuals aged 25-64, regarding females receiving Pfizer, Moderna and AstraZeneca and males receiving Janssen. As facial paralysis was not labelled as an adverse event for the Janssen vaccine, this analysis contributed to signalling the association and warranting further regulatory action.

CONCLUSIONS

The O/E method is a useful approach for signal detection of potential adverse reactions when handling large numbers of ICSRs. Further research is needed to attest to the causality on a clinical basis.

Can Google Trends analysis confirm the public's need for information about the rare association of facial nerve paralysis with COVID-19 or the COVID-19 vaccination?

Facial nerve paralysis or Bell's palsy have been suggested as possible consequences of SARS-CoV-2 infections, as well as possible side effects of COVID-19 vaccinations. Google Trends data have been used to evaluate worldwide levels of public awareness for these topics for pre- and post-pandemic years. The results demonstrate a relatively low public interest in facial nerve paralysis in comparison to other more common COVID-19 related topics. Some peaks of interest in Bell's palsy can most likely be explained as triggered by the media. Therefore, Google Trends has shown public's relatively low awareness of this rare neurological phenomenon during the pandemic.

[Diagnostics and Therapy of Idiopathic Facial Palsy (Bell's Palsy)]

The purpose of this review is to report the knowledge for otolaryngologists on standard of care, latest advances, interesting new findings and controversies about the treatment of Bell's palsy. This review is focusing on the acute phase of the disease. The chronic phase, with incomplete, incorrect or no recovery of the palsy, is described briefly. Treatment with prednisolone alone within 72 hours after onset still is the cornerstone of the treatment. The role of antivirals still is unclear. Since 2009 no new and breakthrough clinical trials with influence on the treatment standards have been performed. A study to clarify the role of prednisolone treatment in children is ongoing. Patient-related outcome measures like the Facial Clinimetric Evaluation Scale and the Facial Disability Index are important tools to assess the subjective severity of the disease and psychosocial impact of Bell's palsy next to the motor deficits. Simplified subjective electronic grading systems like the eFACE and first automated image analysis systems have been introduced. Studies clarifying the role of antivirals for severe cases are urgently needed as well as studies on the role of salvage second line therapy after insufficient response to initial corticosteroid treatment. An international consensus on the outcome measures in diagnostics and follow-up is also needed.