Increased risk of sleep disorder in children who received swine flu vaccine

February 26, 2013

A study published in BMJ today finds an increased risk of narcolepsy in children and adolescents who received the A/H1N1 2009 influenza vaccine (Pandemrix) during the pandemic in England.

The results are consistent with previous studies from Finland and Sweden and indicate that the association is not confined to Scandinavian populations. However, the authors stress that the risk may still be overestimated, and they call for longer term monitoring of the cohort of children and exposed to Pandemrix to evaluate the exact level of risk.

In 2009, A (H1N1) virus spread rapidly, resulting in millions of cases and over 18,000 deaths in over 200 countries. In England the vaccine Pandemrix was introduced in October 2009. By March 2010, around one in four (24%) of healthy children aged under 5 and just over a third (37%) aged 2-15 in a had been vaccinated.

In August 2010 concerns were raised in Finland and Sweden about a possible association between narcolepsy and Pandemrix. And in 2012 a study from Finland reported a 13-fold increased risk in children and young people aged 4-19.

But a lack of reported cases in other countries led to speculation that any possible association might be restricted to these Scandinavian populations.

Narcolepsy is a of excessive daytime sleepiness, often accompanied by sudden muscle weakness triggered by strong emotion (known as cataplexy). To evaluate the risk after vaccination in England, a team of researchers reviewed case notes for 245 children and young people aged 4-18 from sleep centres and child neurology centres across England.

Of these, 75 had narcolepsy (56 with cataplexy) with onset after 1 January 2008. Eleven had been vaccinated before onset of symptoms; seven within six months.

After adjusting for clinical conditions, vaccination at any time was associated with a 14-fold increased risk of narcolepsy, whereas vaccination within six months before onset was associated with a 16-fold increased risk.

In absolute numbers, this means that one in 52,000 to 57,500 doses are associated with narcolepsy, say the authors.

They write: "The increased risk of after vaccination with ASO3 adjuvanted pandemic A/H1N1 2009 vaccine indicates a causal association, consistent with findings from Finland. Because of variable delay in diagnosis, however, the risk might be overestimated by more rapid referral of vaccinated children."

While further use of this for prevention of seasonal flu seems unlikely, they say their findings "have implications for the future licensure and use of AS03 adjuvanted pandemic vaccines containing different subtypes such H5 or H9."

And they conclude: "Further studies to assess the risk, if any, associated with the other A/H1N1 2009 vaccines used in the pandemic, including those with and without adjuvants, are also needed to inform the use of such vaccines in the event of a future pandemic."

Explore further: Adjuvanted flu vaccine associated with child narcolepsy in Finland

More information: www.bmj.com/cgi/doi/10.1136/bmj.f794

Related Stories

Adjuvanted flu vaccine associated with child narcolepsy in Finland

March 28, 2012
A sudden increase in narcolepsy in Finnish children at the beginning of 2010 was likely related to the Pandemrix vaccine used in response to the H1N1 2009 flu pandemic, according to two reports published Mar. 28 in the open ...

Swine flu vaccine linked to child narcolepsy: EU watchdog

September 21, 2012
A swine flu vaccine used in 2009-10 is linked to a higher risk of the sleeping disorder narcolepsy in children and teens in Sweden and Finland, the European Centre for Disease Prevention and Control said Friday.

Swine flu vaccine linked to narcolepsy: Finnish study

September 1, 2011
Researchers in Finland said Thursday they had confirmed a link between the swine flu vaccine and the onset of the sleep disorder narcolepsy in children.

Recommended for you

Pneumonia vaccine under development provides 'most comprehensive coverage' to date, alleviates antimicrobial concerns

October 20, 2017
In 2004, pneumonia killed more than 2 million children worldwide, according to the World Health Organization. By 2015, the number was less than 1 million.

Newly discovered viral marker could help predict flu severity in infected patients

October 20, 2017
Flu viruses contain defective genetic material that may activate the immune system in infected patients, and new research published in PLOS Pathogens suggests that lower levels of these molecules could increase flu severity.

H7N9 influenza is both lethal and transmissible in animal model for flu

October 19, 2017
In 2013, an influenza virus that had never before been detected began circulating among poultry in China. It caused several waves of human infection and in late 2016, the number of people to become sick from the H7N9 virus ...

Flu simulations suggest pandemics more likely in spring, early summer

October 19, 2017
New statistical simulations suggest that Northern Hemisphere flu pandemics are most likely to emerge in late spring or early summer at the tail end of the normal flu season, according to a new study published in PLOS Computational ...

New insights into herpes virus could inform vaccine development

October 18, 2017
A team of scientists has discovered new insights into the mechanisms of Epstein-Barr virus (EBV) infection, as well as two antibodies that block the virus' entry into cells. The findings, published in Proceedings of the National ...

Pair of discoveries illuminate new paths to flu and anthrax treatments

October 17, 2017
Two recent studies led by biologists at the University of California San Diego have set the research groundwork for new avenues to treat influenza and anthrax poisoning.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.