Published Date: 2012-09-22 15:01:41
Subject: PRO/EDR> Influenza (89): France, narcolepsy in H1N1-vaccinated adults
Archive Number: 20120922.1305056
INFLUENZA (89): FRANCE, NARCOLEPSY IN H1N1-VACCINATED ADULTS
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Fri 21 Sep 2012
Source: CIDRAP New [abridged, edited]
French study finds narcolepsy link to H1N1 vaccine in adults
French researchers have found a significant link between one 2009 H1N1 vaccine and narcolepsy in adults, a finding that is likely to prompt some countries to take a fresh look to see if adult cases have surfaced in the wake of pandemic vaccine campaigns. The French findings are part of a larger investigation under way through the Vaccine Adverse Event Surveillance and Communication (VAESCO) Consortium led and funded by the European Centre for Disease Prevention and Control (ECDC). The data are from a case-control study that was partially included yesterday [20 Sep 2012] in a detailed technical report from the ECDC that explored the vaccine-narcolepsy link in 8 European countries, including some that didn't report the problem. Full findings from the French case-control study have now appeared on the Web site of the French Agency for the Safety of Medicines and Health Products (L'Agence nationale de securite du medicament et des produits de sante -- (ANSM).
Only one vaccine has been linked to the narcolepsy cases, Pandemrix, a GlaxoSmithKline (GSK) product that contains its AS03 adjuvant. The vaccine was not used in the United States during the 2009 H1N1 vaccine campaign, but several European countries used it alone or alongside other vaccine formulations. Canada and Brazil also used a very similar GSK pandemic vaccine containing the AS03 adjuvant. Yesterday's ECDC report confirmed the [previously reported] link between narcolepsy and pandemic 2009 vaccination in Finnish and Swedish children, and reported that a sensitivity analysis found a narcolepsy link to vaccinated adults when data were pooled from countries that hadn't already noted an association. The ECDC said more data and case reports will be needed to better understand the link between narcolepsy and the vaccine.
The French researchers used a study protocol that was developed by VAESCO for use in the larger ECDC investigation. However, they noted that the study periods used by the wider study and the analysis specific to France are different, with the French study period starting 6 months later and ending 10 months later. In the report yesterday, French investigators said 51 cases of narcolepsy were reported in French patients who were immunized against the pandemic virus; 47 received Pandemrix, but only 3 received Panenza (a nonadjuvanted vaccine from Sanofi Pasteur), and one received an undetermined product. All of the narcolepsy cases were confirmed by sleep study tests, and 38 involved cataplexy episodes.
During France's pandemic vaccine campaign, about 4.1 million doses of Pandemrix and about 1.6 million vaccinations with Panenza were administered, according to the report. Researchers found that 22 of the narcolepsy cases were in people 16 years old and older and 28 were in children 8 to 15 years old. Symptom onset occurred from 2 days to 15 months after vaccination. 8 patients -- 6 adults and 2 teens -- had a medical or family history that might explain the condition. The investigators reported that overall the same signal seen in Finnish and Swedish children was found in French children, but the link between Pandemrix and narcolepsy was also detected in French adults.
They cautioned that the findings don't show a causal relationship and that a more thorough investigation should be conducted to explore the link further, including possible environmental or genetic factors. ECDC spokesman Giovanni Mancarella said France is the only country in which an association between the pandemic vaccine and narcolepsy has been observed in adults, most of them younger adults. There are more than 100 suspected narcolepsy cases in adults reported in the European Medicine Agency's EudraVigilance database, the ECDC said. Finland's National Institute for Health and Welfare (THL) said today that it is conducting further study on adult cases, according to a statement in Finnish posted on the group's Web site. It said the investigation will focus on 40 to 50 adult narcolepsy cases that were diagnosed between 2009 and 2011. About half of the patients had received the pandemic vaccine. It's not clear why France is the only country that has found the association, Mancarella said, noting that with the data so far, it's impossible to show a causal relationship between the vaccine and narcolepsy in adults.
[Byline: Lisa Schnirring]
[The previously reported link between narcolepsy and pandemic 2009 vaccination in Finnish and Swedish children has been extended now to include vaccinated adults when data are pooled from countries that haven't already reported such an association. However, France is the only country in which the association between the pandemic vaccine and narcolepsy has been observed in adults, most of them younger adults. The significance of these observations has has yet to be evaluated. Likewise the association of the effect with adjuvant-containing vaccine is still inconclusive.
Narcolepsy is a sleep disorder marked by excessive sleepiness during daytime or recurring, uncontrollable episodes of sleep during normal waking hours, plus sudden episodes of muscle weakness (cataplexy). Narcolepsy occurs in about one in 2000 people (in the US and Europe), and much lower in some Asian countries. In some cases, the disorder tends to run in families, but its cause is unknown. Although narcolepsy has no serious medical consequences, it can be disabling and increases the risk of accidents. Narcolepsy persists throughout life but does not affect life expectancy.
Symptoms resemble what happens during REM (rapid eye movement) sleep. The muscle weakness, sleep paralysis, and hallucinations of narcolepsy resemble the loss of muscle tone, paralysis, and vivid dreaming that occurs during REM sleep. For further information see the NINDS (National Institute of Neurological Disorders and Stroke) website at: http://www.ninds.nih.gov/disorders/narcolepsy/detail_narcolepsy.htm. - Mod.CP
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