Vaccine Adverse Event Reporting System Could Miss or Misinterpret Neurological Side Effects of COVID-19 Vaccinations.

We read with interest the article by Frontera et al on the neurological side effects of US Food and Drug Administration–approved anti–SARS‐CoV‐2 vaccines reported to the Vaccine Adverse Event Reporting System (VAERS) by patients, relatives, or health care providers. The study is attractive but raises concerns that should be discussed.

A limitation of the study is that it did not indicate in how many cases the patient, a relative, or a friend, and in how many cases a health care provider or vaccine manufacturer reported to VAERS. Knowing the reporting source is important, because patients or friends are more likely to report symptoms, whereas health care providers or manufacturers are more likely to report diagnoses after inpatient or outpatient evaluation of individual complaints. If the majority of reports come from patients, it is conceivable that serious side effects were overlooked.

Another limitation is the arbitrarily chosen period of 42 days. It is not explained how differential causes of the reported complaints were adequately ruled out. Within a 6‐week period, various causes could have been responsible for the complaints reported, in particular those occurring with a latency of >1 week after vaccination.

It is unclear why certain terms were not coded as Guillain–Barré syndrome (GBS). Immune neuropathy is the umbrella term for GBS. GBS cases coded as immune neuropathy may have been missed. It was not mentioned which category the term immune neuropathy was assigned to. Why was polyradiculitis not categorized as GBS? In addition, convulsion was coded as “seizure,” although convulsions include not only seizures but also nonepileptic seizures, paroxysmal kinesigenic dyskinesia, myoclonuses, or dystonic tremor.

VAERS itself has several limitations. Symptoms reported by individuals are often not objectified by specialists using clinical or instrumental investigations. Double registrations by health care providers and patients cannot be definitively ruled out. False registrations cannot reasonably be ruled out, although knowingly filing a false VAERS report is a violation of US law and punishable by a fine or imprisonment.

It is unclear whether complications reported in the literature, such as small fiber neuropathy, rhabdomyolysis, reversible cerebral vasoconstriction syndrome, cerebral vasculitis, hypophysitis, Parsonage–Turner syndrome, or Tolosa–Hunt syndrome, have been reported to VAERS and what category of neurological side effects these have been assigned.

We disagree that the beneficial effects of anti–SARS‐CoV‐2 vaccines outweigh the rare side effects. Every patient with a serious, disabling, or fatal side effect is one too many. Efforts should be made to make anti–SARS‐CoV‐2 vaccines safer.

Potential Conflicts of Interest

Nothing to report.

Data Availability

All data are available from the corresponding author.