Many individuals are concerned about a potential link between COVID-19 vaccines and seizures. This article examines the scientific evidence regarding any connection between vaccination and seizure activity, explores the risk of seizures from COVID-19 illness itself, and summarizes guidance from leading health authorities.
Understanding Seizure Activity
A seizure represents a sudden, uncontrolled disturbance in the brain’s electrical activity. This abnormal electrical discharge can lead to a range of manifestations, including changes in consciousness, altered behavior, or involuntary movements. While seizures can be a symptom of various underlying health conditions, their fundamental nature involves a temporary disruption of normal brain function.
Examining the Evidence
Large-scale surveillance systems continuously monitor adverse events following vaccination, including seizures. In the United States, the Vaccine Adverse Event Reporting System (VAERS), co-managed by the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA), collects reports from individuals, healthcare providers, and manufacturers. It is important to understand that a report to VAERS does not confirm that the vaccine caused the event; it serves as an early warning system for potential safety signals.
Data from VAERS indicate an estimated incidence of 3.19 seizures per 100,000 people per year following COVID-19 vaccination, compared to 0.090 for influenza vaccines. This difference in reporting rates does not establish a causal relationship but highlights the need for continued monitoring. Most reported seizures in this system occurred within approximately two days of vaccination. Similarly, the Yellow Card Scheme in the United Kingdom and EudraVigilance in Europe collect suspected adverse reactions, which are reviewed to detect patterns. These systems also emphasize that reported events are suspicions, not confirmed causal links.
Scientific studies have generally not found a causal link or a significantly increased risk of seizures directly attributable to the COVID-19 vaccines for the vast majority of people. A meta-analysis of six randomized, placebo-controlled clinical trials found no statistically significant difference in the risk of new-onset seizures between vaccinated individuals and placebo recipients. Studies from Hong Kong and Mexico also concluded that seizures following COVID-19 vaccinations are exceedingly rare events, with very low incidence rates. These studies often noted that reported seizure events frequently occurred in individuals with a pre-existing history of seizures or other identifiable causes.
While some rare neurological conditions, such as Guillain-Barré Syndrome, have been investigated in relation to vaccines, these are distinct conditions and seizures are not a direct outcome. For children aged 2 to 5 years, one study identified a statistical signal for seizures, predominantly febrile seizures, after certain mRNA vaccines, with a median onset of two days. However, this signal requires cautious interpretation, as it may be a research artifact, and the CDC’s post-marketing surveillance has not identified a widespread safety concern for febrile seizures in this age group. Overall, if seizures occur post-vaccination, they are often transient, and studies have shown that people with epilepsy are not at a higher risk of adverse effects from vaccination.
Seizure Risk from COVID-19 Illness
Beyond vaccine considerations, it is important to understand the neurological impact of COVID-19 infection itself. The SARS-CoV-2 virus can affect the brain and nervous system, leading to various neurological complications, including seizures. Seizures are considered an uncommon complication of the illness, occurring in less than 1% of infected individuals. However, in hospitalized patients, seizures have been observed in a higher percentage, with some reviews indicating about 2.2% of hospitalized individuals experiencing seizures, often with a pre-existing history.
Studies have consistently shown that COVID-19 infection increases the risk of seizures and epilepsy compared to other respiratory illnesses like influenza. For instance, individuals who have had COVID-19 are approximately 80% more likely to develop epilepsy or seizures within the first year following infection than those who were not infected. The incidence of seizures within six months of COVID-19 infection was found to be 0.81%, compared to 0.51% after influenza.
The mechanisms by which COVID-19 can trigger seizures include low oxygen levels (hypoxia), systemic inflammation, and, in some instances, viral-induced brain inflammation or direct brain damage. Seizures can occur during the acute phase of the illness or as a long-term complication, a component of what is known as Long COVID. The risk of experiencing neurological complications, including seizures, is significantly higher from COVID-19 infection itself than from receiving a COVID-19 vaccine.
Guidance from Health Authorities
Major global and national health organizations consistently monitor the safety of COVID-19 vaccines. The CDC, the World Health Organization (WHO), and the European Medicines Agency (EMA) all maintain robust surveillance systems to track any potential side effects. Their assessments continue to affirm that the benefits of COVID-19 vaccination, in terms of preventing severe illness, hospitalization, and death, far outweigh the rare risks associated with vaccination.
These authorities emphasize that the detection of a safety signal, such as a reported increase in a particular adverse event, prompts further investigation to determine if there is a true causal link. For instance, while some reports of febrile seizures in very young children post-vaccination have been noted, the CDC’s ongoing surveillance has not identified this as a widespread safety concern for mRNA vaccines. Healthcare providers are required to report serious adverse events to systems like VAERS, and anyone can submit a report. Individuals who experience any concerning symptoms after vaccination should consult with a healthcare professional for appropriate evaluation and guidance.