Jul 21, 2011 (CIDRAP) – Europe's drug regulatory agency today released its final review of a link between narcolepsy and the Pandemrix 2009 H1N1 vaccine, which recommends a labeling change that limits the vaccine's use in children and teens to when protection is needed and seasonal trivalent vaccine isn't available.
Some countries, primarily Scandinavian ones, have reported link between the vaccine and narcolepsy in young people. Pandemrix, made by GlaxoSmithKline (GSK), is one of the 2009 H1N1 vaccine used in Europe during the pandemic, and it's unclear how many doses are still on the market. It contains the AS03 adjuvant.
The European Medicines Agency (EMA) said today in a press release that its Committee for Medicinal Products for Human Use (CHMP), however, has confirmed that the vaccine's overall risk-benefit balance is positive.
The agency said in the release that "in persons under 20 years of age Pandemrix may only be used if the recommended seasonal trivalent influenza vaccine is not available and if immunisation against H1N1 is still needed (eg, in persons at risk of the complications of infection)."
The CHMP launched a review of the vaccine-narcolepsy in August 2010, based on a request from the European Commission. Today's labeling change recommendation follows an interim one in April asking GSK to warn about the risk in young people and advise healthcare providers to perform an individual benefit-risk assessment before administering Pandemrix.
In making its recommendation today, the EMA said it took into consideration epidemiologic studies conducted in Finland and Sweden, safety and surveillance data from several other EU countries, and preliminary findings from an eight-country study coordinated by European Centre for Disease Prevention and Control (ECDC). It also incorporated feedback from an expert meeting that discussed that link.
The EMA said the Finnish and Swedish studies were well designed, showing a 6- to 13-fold increase risk of narcolepsy in young people who had received the Pandemrix vaccine. It added that link has not been found in adults 20 and older.
Though the preliminary ECDC findings confirmed the narcolepsy link in Finland, the EMA cautioned about extrapolating the findings to other countries, especially ones where vaccination coverage with Pandemrix was lower.
The vaccine likely interacted with genetic or environmental factors that could boost the risk of narcolepsy, the EMA said, adding that several studies in the European Union are under way to explore other possible connections.
"Exposure to specific infectious diseases (including H1N1) at different ages, particularly upper respiratory infections, may have contributed to the observations in the Nordic area," the EMA said, adding that more research is needed to address such possibilities.
GSK said in a statement today that the labeling change will replace the advisory to clinicians that the EMA recommended in April. The company said it would continue to work closely with the EMA and other regulators to explore the possible link. It added that final results from the ECDC study and an epidemiological study that it is conducting in Canada are needed to shed more light on narcolepsy cases in people who received Pandemrix.
The company also said it will conduct more research on the possible link and include input from independent experts, per an agreement with the EMA.
So far 31 million doses of Pandemrix have been administered in 47 countries, GSK said. It has received 335 reports as of Jul 6 of narcolepsy in people who were immunized with Pandemrix, of which 68% were from Finland and Sweden.
Jul 21 EMA press release
Apr 15 CIDRAP News Scan