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Handful of narcolepsy cases sparks pandemic vaccine probe in Europe

The European Medicines Agency launched a review on 27 August of a putative link between GlaxoSmithKline’s Pandemrix pandemic H1N1 vaccine and a handful of cases of narcolepsy – a rare sleeping disorder. A temporal association between vaccination and development of the disease has been reported in 15 children in Finland and six in Sweden, although that by no means proves the vaccine caused them. The review will analyse whether there is any link or not, and whether the cases represent or not an abnormal increase on the usual baseline levels that would be expected: the prevalence of narcolepsy – which has a genetic component, and can be triggered by infections – is estimated generally at around 0.045% of the population, and in Finland 6 cases in children per year.

On 24 August, Finland’s National Institute for Health and Welfare announced on the advice of its National Advisory Committee on Vaccines, that it was suspending vaccination with Pandemrix until the link was investigated. It added that as there’s no flu in the country at the moment, there isn’t any immediate need anyway to vaccinate, while much of the country’s population already has immunity to H1NI either through vaccination or having contracted the virus. The European Medicines Agency will hold a meeting in September to decide whether any provisional measures on the use of Pandemrix are called for pending completion of the investigation.

Side effects of vaccines are part of any public health response risk equation. No amount of clinical trials can detect rare side-effects in advance, as statistically one would need impractically large population-size experimental cohorts to pick up very low incidence rates. Instead, regulators use pharmacovigilance once vaccines have been deployed to spot early on any problems. With some 30.8 million Europeans, including this author, already vaccinated with Pandemrix since autumn 2009, no serious safety concern has been detected.

Although anti-vaccine groups will no doubt leap on the preliminary reports from Scandinavia to scream “side-effects,” the sober reality is that not using modern and safe vaccines causes many more people to become ill or die than any rare side-effect.

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