# 7312
The Pandemrix/Narcolepsy saga – which began in August of 2010 when reports linking the vaccine to increased levels of narcolepsy in children first surfaced – has taken another turn today with the Finnish National Institute for Health and Welfare announcing that adults who received the vaccine saw an increased incidence of the rare neurological condition, as well.
We’ll get to today’s statement momentarily, but for those who have not followed this story closely, a quick review:
Pandemrix was the adjuvanted pandemic H1N1 flu shot developed by GlaxoSmithKline (GSK) and distributed to more than 30 countries beginning in the fall of 2009. This vaccine included a squalene-based component called AS03, used as a adjuvant.
Adjuvants are additives that are used to increase the immune response to a vaccine. Their use can allow the `stretching’ of the vaccine supply, as shots can contain a smaller amount of antigens.
While they have been used in Europe and in Canada, adjuvanted flu vaccines have not been licensed for use in the United States.
Despite a series of conflicting and incomplete reports, the European Medicines Agency issued a statement in July of 2011 recommending:
In persons under 20 years of age Pandemrix to be used only in the absence of seasonal trivalent influenza vaccines, following link to very rare cases of narcolepsy in young people.
Finland convened a Task Force Report On Pandemrix-Narcolepsy Link that confirmed an association – as yet unexplained – between receipt of the vaccine and an increase in narcolepsy in children between the ages of 4 and 19.
In September of 2012, the ECDC released a 164 page technical report called Narcolepsy In Association With Pandemic Influenza Vaccination in which the summary found:
The case–control study confirms an association between vaccination with Pandemrix® and an increased risk of narcolepsy in children and adolescents (5 to 19 years of age) in Sweden and Finland that originally reported on this issue (signalling countries). No such association was found in adults in these two countries.
And in February of this year, the HPA released a report:
Pandemic flu vaccination linked to narcolepsy in UK children
27 February 2013
Health Protection Agency (HPA) scientists have found evidence of an association between Pandemrix flu vaccination and narcolepsy in children in England, according to the findings of a study published in the British Medical Journal. These findings are consistent with previous studies from Finland and Sweden which identified a similar association.
The exact mechanism behind this Pandemrix-Narcolepsy link remains a medical mystery. Our understanding of this neurological disorder is very limited, as well.
This study found the absolute risk of a child developing narcolepsy from the Pandemrix flu shot appeared to be about 1 in 55,000. The authors warn that:
`Our findings have implications for the future licensing and use of adjuvanted pandemic vaccines’.
Fast forward to today, and the Finnish National Institute for Health and Welfare reports an increase in narcolepsy among adults who received this particular vaccine, as well.
Increased risk of narcolepsy observed also among adults vaccinated with Pandemrix in Finland
23 May 2013
Adults aged less than 65 years who had received Pandemrix-vaccine in 2009 and 2010 to protect against the pandemic influenza A(H1N1) had an increased risk of developing narcolepsy during the first months following vaccination compared to those unvaccinated in the same age group. According to the most recent investigation conducted by the National Institute for Health and Welfare (THL), the vast majority of adults who fell ill with narcolepsy during 2009-11 were under 40 years of age. The risk of falling ill with narcolepsy following vaccination had returned to pre-vaccination levels by eight months after the vaccination.
In Finland during 2009–11, altogether 25 adults developed narcolepsy, with 23 of the patients under 40 years of age and none older than 64 years of age. Pandemrix vaccine had been received by 18 of the confirmed narcolepsy patients. Vaccination coverage in this age group was 50 per cent.
Depending on the assumptions used in the analysis, the risk of developing narcolepsy in Pandemrix-vaccinated adults aged between 20 and 64 years of age was 3–5-fold compared to non-vaccinated persons of the same age. The increased risk of narcolepsy attributed to vaccination with Pandemrix in adults was 1/100 000, whereas in children it was 6/100 000. These numbers are based on nationwide records from hospital and primary care registers, followed by an audit of the accuracy of diagnoses by neurologists and a panel of experts using individual medical records.
Increase in adult narcolepsy following vaccination previously reported in Sweden and France
A French study published in September 2012 was the first to report an increase in adult narcolepsy following Pandemrix-vaccination. However, the French study report was preliminary and therefore the results have been interpreted with caution. In March 2013, Swedish medical authorities published a registry-based study that reported a two-fold increase in young adults following Pandemrix-vaccination. In contrast to the study reported in Sweden, both the diagnoses and the vaccination records collected from the registers were validated in the THL investigation. The risk in adults has also been studied in a collaborative European-wide case-control study in the Netherlands, Italy, Norway, the UK and Denmark, but so far no increase has been observed in these countries.
It’s worth noting that in terms of actual numbers, we’re talking a only a handful of cases here; 25 total adult narcolepsy cases between 2009 and 2011, 18 of whom received the vaccine.
So in absolute terms, the chances of developing narcolepsy (as a child or an adult) after receiving this vaccine were pretty low; perhaps 1 or 2 out of 100,000.
While the Pandemrix vaccine is no longer in use, should we face another influenza pandemic threat anytime soon, decisions regarding the use of adjuvanted vaccines – which could stretch potentially life-saving vaccine supplies to cover more people - will have to be made.
Decisions on what constitutes an `acceptable risk’ would no doubt vary depending upon the perceived virulence of any given pandemic outbreak.
Which makes pinning down the exact cause of these increases in neurological adverse effects – and finding ways to prevent them - of considerable importance.
