And U.S. officials said they were changing the labeling on a vaccine made by Australia's CSL Ltd because it appears to have caused a higher than usual rate of seizures in children.

Sanofi Aventis said it was shipping 70 million doses of seasonal flu vaccine -- its largest production run ever -- and GlaxoSmithKline said it was shipping 30 million doses of partner ID Biomedical's FluLaval vaccine.

This year we also are launching Fluzone High-Dose (Influenza Virus Vaccine) for people 65 years of age and older, Sanofi said in a statement.

Tests have shown that people over 65 produce a weaker immune response but get better protection when immunized with a stronger vaccine.

Glaxo said it would begin shipping its own flu vaccine, Fluarix, within a few weeks. Other vaccine makers for the U.S. market include Novartis and AstraZeneca unit Medimmune.

BROAD RECOMMENDATION

The U.S. Centers for Disease Control and Prevention recommends that everyone be vaccinated against seasonal flu this year, the most universal recommendation yet for flu vaccines. The CDC says manufacturers have forecast they will have 170 million doses of flu vaccine for the 2010-2011 U.S. flu season.

Last year the U.S. government shipped 162 million doses of H1N1 vaccine but only 90 million were used. About 40 percent of Americans in the groups advised to be vaccinated ever go get immunized.

Most years, seasonal influenza infects between 5 percent and 20 percent of the U.S. population and kills 36,000 people. It puts about 200,000 into the hospital.

But last year the new pandemic of H1N1 swine flu replaced virtually all other flu strains. It was about as deadly as seasonal flu but instead of hitting the elderly, the most severely ill were younger adults, children and pregnant women.

The 2010-2011 seasonal flu vaccine will include the H1N1 swine flu vaccine, plus the most common strains of H3N2 and influenza B.

FOCUS ON AFLURIA

The labeling for one vaccine, CSL Limited's Afluria, has undergone changes this season to inform health care providers about an increased incidence of fever and febrile seizure, which was seen in young children, mainly those younger than 5 years, following administration of the 2010 Southern Hemisphere formulation of CSL's influenza vaccine, the U.S. Food and Drug Administration said in a statement.

CSL Limited will not be supplying the United States with the 0.25 milliliter single-dose, prefilled syringes, which are used in very young children.

The FDA said it was asking CSL to conduct a study of its vaccine in children.

Flu vaccines have to be made fresh every year to match the circulating strains of the virus. They are made using old technology involving chicken eggs, and manufacturers cannot always predict how much vaccine they will be able to produce and when.

A few companies can now make vaccine in cells and governments are working with industry to switch over to faster and more predictable ways to make flu vaccines.

Australia Medicine