FLU NEWS SCAN: Pandemrix and narcolepsy, H1N1 border screening, H5N1 seroprevalence

Apr 19, 2012

Ireland reports Pandemrix links to narcolepsy in kids, teens
Irish children and teens receiving the Pandemrix 2009 pandemic H1N1 (pH1N1) vaccine had a statistically significant 13-times-greater risk of developing narcolepsy than did children not receiving the vaccine, according to a report from the country's health department today. Investigators found 32 cases reported from April 2009 that met the case definition of narcolepsy, 28 of which were in 5- to 19-year-olds. They established a narcolepsy incidence of 5.8 (95% confidence interval [CI], 3.5-9.0) per 100,000 person-years in vaccinated versus 0.5 (95% CI, 0.2%-1.0%) per 100,000 person-years in unvaccinated patients, which translated into a "highly statistically significant" 13-fold increased risk (95% CI, 4.8-34.7). Dr Darina O'Flanagan, director of the Health Protection Surveillance Centre, said in an Irish Department of Health (DOH) press release today, "International experts agree that a number of factors are likely to have contributed to the increased risk of developing narcolepsy and further research is required to understand the exact causative mechanism." The European Centre for Disease Prevention and Control (ECDC) added in its own release that the report's "powerful epidemiological association" is similar to those reported by Finland and Sweden. Last summer European regulators restricted the use of Pandemrix in children and young adults under 20 years old.
Apr 19 Irish DOH press release
Apr 19 ECDC news release
Full DOH report
Jul 21, 2011 CIDRAP News story "EMA narcolepsy review restricts Pandemrix use in kids, teens

Chinese study finds H1N1 border screening ineffective
Border entry screening was unlikely to have delayed the spread of pH1N1 flu into China by more than 4 days, researchers reported yesterday in Emerging Infectious Diseases. Chinese and UK scientists analyzed data from multiple surveillance systems and clinical investigations to determine transmission patterns of pH1N1 in China from May through November 2009 and assess whether entry screening and holiday school closures affected transmission. They found that school closures for 8 days of national holidays in October reduced the effective reproduction number by 37% (95% confidence interval, 28%-45%). They also found that border entry screening detected at most 37% of pH1N1 cases in international travelers, with 89% of them identified as having fever at the time of entry into the country. The authors said their data parallel European and US results, and they conclude, "Border entry screening during the influenza pandemic delayed spread in China by a few days, at most."
Apr 18 Emerg Infect Dis study

 Study finds H5N1 antibodies in 2.6% of Chinese poultry workers
A study of blood samples from 306 poultry workers in a Chinese province that has had H5N1 avian flu outbreaks and two human cases found that 8 workers (2.6%) had serologic evidence of H5N1 infection. Reporting yesterday in BMC Infectious Diseases, Chinese investigators said they examined samples from three counties in Jiangsu province and used a hemagglutinin inhibition assay titer of 1:160 as a measure of seropositivity. They found the rate of seropositive samples varied from 0 to 5.4% among the three counties but did not specify individual titers or history of exposure to H5N1 viruses. They also reported that, of the two strains used in testing, no samples were positive for a 2010 H5N1 strain; all positive samples were for a 2005 H1N1 strain. The authors conclude, "Our findings suggest that avian-to-human transmission of influenza H5N1 virus remains low in China."
Apr 18 BMC Infect Dis abstract

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