House committee continues questions on US flu season response
Bipartisan leaders of the US House oversight and investigations subcommittee yesterday continued to press federal health officials for answers about seasonal flu preparedness in the wake of a mismatch between the vaccine and the main circulating strain last season.
In a letter to Health and Human Services (HHS) secretary Sylvia Burwell, they again raised concerns about the high death rate in older people last flu season, protection gaps with current vaccines, and whether more steps are needed to improve the nation's response to future flu seasons.
Yesterday's letter was a follow-up to a Feb 3 hearing on the response to the 2014-15 flu season and responses to five letters they sent on Mar 9 to different government departments that play a role in flu preparedness and response.
In the 4-page letter, the lawmakers requested more information by Aug 12 on eight different points. For example, lawmakers asked about contingency plans in case a mismatch occurs during the upcoming flu season, if a public emergency would ever be declared for a severe flu season, and what criteria might trigger the federal consideration of a monovalent "rescue" vaccine to shore up protection, a step that they learned was pursued during the 1986-87 season because of a drifted H1N1 strain.
Also, the committee asked if greater emphasis should be placed on antiviral medications and if vaccine advisors should consider expediting discussions on whether to recommend routine use of high-dose flu vaccine for seniors.
Regarding the vaccines themselves, the group asked if officials have ever measured the outcomes against the disease for doses it purchases through federally funded vaccine programs and if they would ever allow an unlicensed flu vaccine to be used under an emergency use authorization.
Jul 29 House subcommittee letter
Mar 10 CIDRAP News scan "Lawmakers push for more details on flu strain mismatch"
CDC study points to low H5N2, H5N8 risk in humans
A new study by researchers at the US Centers for Disease Control and Prevention (CDC) determined that, based on findings in mice, ferrets, and cell culture, the H5N2 and H5N8 avian flu viruses that have ravaged US poultry this year pose a low pandemic risk to people.
The two strains were able to cause severe disease in mice only at high doses. And although they replicated well in the respiratory tract of ferrets, they did not spread between the animals. The study appeared yesterday in the Journal of Virology.
In mice, viruses were detectable in lung tissue, but the animals had less-severe disease compared with Asian H5 virus.infections. Infected mice did not exhibit severe disease unless they received very high doses of the virus.
Transmission experiments using ferrets showed the US H5 strains did not spread in uninfected ferrets placed in the same cage as infected ones. Illness in these animals was generally mild, and the viruses did not spread to multiple organs. These results are consistent with studies of H5N8 viruses in South Korea, the CDC said in a news release.
In lab cultures of human bronchial epithelial cells, H5N2 and H5N8 replicated at significantly lower levels than Asian H5N1 viruses. Though the viruses did replicate, it was at levels akin to the 2009 H1N1 influenza virus.
The authors concluded, "Although the recently isolated H5N2 and H5N8 viruses displayed moderate pathogenicity in mammalian models, their ability to rapidly spread among avian species, reassort, and generate novel strains underscores the need for continued risk assessment in mammals."
Jul 29 J Virol abstract
Jul 29 CDC news release
Ghana reports four H5N1 outbreaks in capital region
Authorities in Ghana have reported four more H5N1 avian flu outbreaks, all in the area around Accra, the capital, continuing a string of incidents that began early in June.
The new outbreaks killed 7,786 of 9,181 susceptible birds, and another 1,295 have been destroyed to prevent further spread, Ghanaian officials said in a report to the World Organization for Animal Health (OIE) yesterday.
Most of the affected birds were layer chickens, but ducks, pullets, and cockerels (young roosters) were also involved, the report said. The largest holding had 6,715 layers and ducks, of which 6,326 died of the infection. The outbreak there began Jun 15; the other three started on Jul 18.
The authorities have carried out the standard responses, including quarantine and disinfection of the farms and restrictions on poultry movements.
Jul 29 OIE report
