MicrobeWorld

The United States still has 71 million doses of H1N1 swine flu vaccine that have not been used, but it is not yet time to throw them out, the federal government said on Monday. States and other providers should hang on to the vaccine and continue to offer them to people until drug companies can start distributing seasonal vaccine for the coming influenza season in the autumn, said Health and Human Services Department spokesman Bill Hall.

Senator Chuck Grassley, the ranking Republican on the Senate Finance committee, released a letter on Monday that he sent to HHS secretary Kathleen Sebelius asking her how much vaccine was left over and when it would expire. H1N1 swine flu is still technically causing a pandemic and health officials say anyone who has not been vaccinated should still try, in case it causes a third wave of serious disease.

Health experts consider swine flu likely to join the mix of seasonal flu viruses and it will be included in the seasonal flu vaccine for 2010-2011, which will also contain two other flu strains. When the H1N1 virus started spreading in April, HHS and its agencies, along with commercial flu vaccine makers, rushed to formulate and make a vaccine.

Influenza vaccines are made using old and unwieldy methods that require incubating the virus in chicken eggs, and the process always takes months. Vaccine started rolling out in October and the U.S. eventually ordered 229 million doses from its five licensed makers -- Novartis, AstraZeneca unit MedImmune, Sanofi Aventis, GlaxoSmithKline and Australian vaccine maker CSL. Sebelius said last month that 162 million doses were produced and distributed, but only 90 million actually got into people's arms or noses.