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GENEVA (Reuters) - This year's seasonal flu vaccine in the northern hemisphere should include protection against three strains, including the pandemic H1N1 virus, the World Health Organization (WHO) recommended on Thursday.
The composition, announced after a four-day meeting of experts, means H1N1 swine flu vaccine still held by drugmakers in bulk form may be used for part of the seasonal flu vaccine mix for autumn/winter 2010/2011, WHO's flu expert Keiji Fukuda said.
Some countries, including Germany, France and the United States, cut back their orders of the H1N1 flu jab after people were slow to take them up. The fact that people needed only one dose, not two, also contributed to oversupply.
"The inclusion of the H1N1 pandemic virus in the influenza vaccine does not signal that the pandemic is over," Fukuda told reporters. "This virus is expected to be a significant threat to people as we go into the fall and winter period."
Young people, especially those with chronic medical conditions, and pregnant women continue to be at higher risk of infection and viral pneumonia from the H1N1 virus, he said.
WHO's emergency committee of influenza experts will meet on February 23 to evaluate whether the world is moving out of the pandemic, but the H1N1 virus is expected to remain the dominant virus circulating worldwide regardless, he said.
"The post peak period means that we continue to be in a pandemic," Fukuda said, but also means the virus is declining and flu infection rates are getting closer to normal.
The end of a pandemic is "more of a tailing off phenomenon."
H1N1 vaccine component held by pharmaceutical companies in bulk form -- but not that already put into syringes or vials -- may be used for the seasonal vaccine mix, he said.
"If they have the vaccine strain which is already made up and can be used, then they're ahead of the game," Fukuda told Reuters after a public WHO session attended by drug companies.
The other recommended vaccine strains are H3N2 -- which like H1N1 is a type of influenza A -- and influenza B.
National health authorities would have to decide whether to combine the three strains into a single "trivalent" shot, offer three separate vaccines, or use a separate H1N1 shot and combine the other two in one shot," he said.
"For many countries, I think the answer is that a trivalent vaccine would make sense," Fukuda said.
Some 200 million people have received the H1N1 pandemic vaccine so far, but Fukuda said there was no reason to suggest getting the trivalent vaccine would pose any problems for them.
Vaccine makers such as GlaxoSmithKline and Sanofi-Aventis need the WHO's vaccine guidance to start formulating shots for the northern hemisphere's 2010/11 mix. The flu season usually begins around November.
Meirion Evans, chair of the Health Protection Committee at the UK Faculty of Public Health, told Reuters pandemic H1N1 flu may well return in the autumn in the form of seasonal flu.
"People who suffered from pandemic H1N1 flu or who have had the pandemic vaccine will already have some immunity. However, the seasonal flu vaccine is still recommended for everyone aged 65 years and over, and for people of any age in flu risk groups."
(For the WHO recommendation for the northern hemisphere, go to: here)
Additional reporting by Jonathan Lynn in Geneva and Kate Kelland in London; Editing by Jonathan Lynn and Janet Lawrence