Written by Jessica Patella, ND. In the UK, 24% of healthy children under 5 years old received the vaccine, Pandemrix. They were 14.3 times more likely to suffer from narcolepsy (extreme daytime sleepiness).
Narcolepsy is a disorder of excessive daytime sleepiness that is sometimes accompanied with a loss of muscle tone (cataplexy) (1). It is most common in 10-19 year olds, although it can occur at any age (1,2). Recent research has discovered an increase in narcolepsy in children and adolescents that received the H1N1 vaccine in Europe (1).
The particular H1N1 vaccine in question contained the AS03 adjuvant (Pandemrix) and was introduced in October 2009 in Europe (1). Adjuvants are added to vaccines to increase the immune response. By March 2010 an estimated 24% of all healthy children less than 5 years old, and 37% of children at risk for the flu from 2-15 years old, received this vaccine in England (4).
The recent research in England included a review of 245 clinical records identified from 16 pediatric neurology centers and hospital databases with symptoms of narcolepsy (1). 130 of the cases were excluded because they were before the vaccine was administered and 23 were excluded because the diagnosis of narcolepsy was not confirmed by the neurology centers (1). This left 92 cases for review by a panel of narcolepsy experts that were blinded to the reason of the study (1). Of the 92 cases, 66 were confirmed by the panel to have narcolepsy and 9 were labeled as probable narcolepsy (1).
Of the 75 cases of narcolepsy, 11 definite cases showed the patient received the H1N1 vaccine with AS03 adjuvant (Pandemrix), 3-6 months before onset of narcolepsy (1). The ages of the patients ranged from 3-16 years old (1). Children aged 36 months through adults are recommended to receive 0.5 ml vaccine per dose and 1 to 2 doses per year. Those getting 1.5 doses per year between 3 and 16 would receive 21 doses and result in 10.9 to 12.1 cases of narcolepsy per 100,000 children.
This shows a significant increased risk of narcolepsy in children who received an H1N1 AS03 attenuated vaccine. The increase equated to about a 14.4 odds ratio of narcolepsy occurring (1). A similar result was discovered in Finland, where researchers reported a 13-fold increased risk of narcolepsy after vaccination in children from 4-19 years old, within 3-6 months (with an incidence of 1 in 16,000 per dose) (5). This is important to note, because it was previously thought the association of narcolepsy and the H1N1 AS03 vaccine was restricted to the Scandinavian population (1).
In conclusion, an increased risk of narcolepsy in children and adolescents who received the H1N1 vaccine with AS03 adjuvant (Pandemrix) was observed in the English population (1). The vaccine was administered throughout the European Union and additional countries would need to conduct similar research to determine if the results are similar throughout Europe.
Source: Miller, Elizabeth, et al. “Risk of narcolepsy in children and young people receiving AS03 adjuvanted pandemic A/H1N1 2009 influenza vaccine: retrospective analysis.” Bmj 346 (2013): f794.
© 2017 BMJ Publishing Group Ltd
Posted May 13, 2013.
References:
- Miller E, et al. Risk of narcolepsy in children and young people receiving AS03 adjuvanted pandemic A/H1N1 2009 influenza vaccine: retrospective analysis. 2013 BMJ doi:10.136bmj.f794.
- Longstreth WT Jr, et al. The epidemiology of narcolepsy. Sleep 2007;30:13-26.
- Silber MH, et al. The epidemiology of narcolepsy in Olmsted County, Minnesota: a population-based study. Sleep 2002;25:197-202.
- Pandemic H1N1 (swine) influenza vaccine uptake amongst patient groups in primary care in England 2009/10, DH/HPA, DH/HPA28, Oct 2010.
- Nohynek H, et al. AS03 adjuvanted AH1N1 vaccine associated with an abrupt increase in the incidence of childhood narcolepsy in Finland. PLoS One 2012;7:e33536.
