Study: Swine flu itself may trigger narcolepsy

Pandemrix flu vaccine suspected in Europe of having caused narcolepsy cases was not used in China

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Swine flu may trigger narcolepsy, claims a study published on Monday.
      The study concentrated on the medical records of nearly a thousand Chinese patients, who had contracted narcolepsy between 1998 and 2011. The study was published by the American neurology journal Annals of Neurology.
      A similar connection has been tentatively suggested by previous studies as well, but none of them covered such a large number of subjects, 906 in all.
     
”The results strongly suggest that the wintertime respiratory infections, such as influenza (including swine flu) and/or a streptococcal infection, can trigger narcolepsy”, writes Emmanuel Mignot from Stanford University in the United States. Mignot was part of the team that conducted the research.
      The researchers interviewed more closely 154 patients whose symptoms began after October 2009, in other words after the swine flu outbreak.
      The largest number of narcolepsy cases were recorded in April, or 5-7 months after the peak of the outbreak.
     
In Europe, the increase in the number of narcolepsy cases has been connected with the Pandemrix flu vaccine, which was used to inoculate people against swine flu.
      This vaccine was not used in China. Also, in China, only six per cent of those who contracted narcolepsy had been given any kind of vaccination against swine flu.
      Mignot feels it is possible that Pandemrix caused a strong immune response, and that it is for this reason the vaccine has been associated with the narcolepsy risk in Finland, for instance.
     
According to research professor Outi Vaarala from the National Institute for Health and Welfare (THL), this is pure speculation.
      “In my opinion, based on the Chinese study one cannot draw the conclusion that narcolepsy would be a strong immune response caused by the Pandemrix vaccine against the virus.”
     
THL will publish next week its final report of a study focusing on the narcolepsy incidents in Finland. According to Vaarala, the study did not indicate that those children who contracted narcolepsy would have had more influenza-type illnesses than children on average at the time.
      “The study conducted in China points out the same fact that has already been known: contracting narcolepsy may have a connection with an influenza or streptococcal infection. In my opinion, no more far-reaching conclusions can be drawn from it.”
      By March of this year, THL had received nearly 70 reports of narcolepsy or catalepsy attributed to the earlier vaccine campaign against the H1N1 or swine flu virus.
     


Previously in HS International Edition:
  Swine flu vaccine and narcolepsy: questions and answers (2.2.2011)
  Narcolepsy diagnosed in 41 children vaccinated for H1N1 last year (14.12.2010)
  H1N1 vaccinations suspended over narcolepsy scare (25.8.2010)
  Hundreds of reports of harm from swine flu shots (14.3.2011)

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