Published: 28-12-2012 00:00 | Updated: 08-06-2015 13:19

Scientists dismiss the link between epilepsy and the flu vaccine

A new register study from Karolinska Institutet finds no increased risk of epilepsy for the controversial flu vaccine Pandemrix. In the study, which was conducted in three Swedish counties, epileptics were monitored for three months before and three months after they had been vaccinated against the pandemic H1N1 influenza virus, also known as swine flu.

"As epileptics in Sweden are recommended to get vaccinated against influenza each year, it is important to investigate if there is an increased risk of epileptic seizures resulting from the vaccination. Our study provides information that can help physicians to make decisions in regard to the vaccination of epileptics in the event that H1N1 would reach Sweden again", says Lisen Arnheim-Dahlström, who led the study at the Department of Medical Epidemiology and Biostatistics.

Pandemrix has become known through the cases of narcolepsy in children and teenagers that were presented following the vaccination campaign against the pandemic influenza in the winter of 2009-2010. However, prior to this being brought to light, the European Medicines Agency (EMA) had also received reports of epileptic seizures following the vaccination of previously known epileptics.

In the current study, published in the scientific periodical, the British Medical Journal (BMJ), researchers have therefore studied the association between vaccination with Pandemrix and an increased risk of epilepsy. The results show that there was no increased risk of epileptic seizures following vaccination, regardless of whether or not they were diagnosed with epilepsy during the year prior to the follow-up. A total of more than 370,000 people were vaccinated against H1N1 influenza during the winter of 2009-2010 in the three counties included in the study; Kalmar, Värmland and Norrbotten.

Epilepsy is a neurological, chronic illness that manifests in sudden seizures due to the electrical discharge of cerebral neurons. There are several reasons for these seizures, such as previous scarring in the brain, infections or other stresses to the brain. In most cases, no underlying medical explanation is ever found. Approximately 0.5-1% of the Swedish population, corresponding to around 60,000 people, are currently diagnosed with epilepsy.


Risk of presentation to hospital with epileptic seizures after vaccination with monovalent AS03 adjuvanted pandemic A/H1N1 2009 influenza vaccine (Pandemrix): self controlled case series study.
Arnheim-Dahlström L, Hällgren J, Weibull C, Sparén P
BMJ 2012 Dec;345():e7594