It remained uncertain, however, whether there would be enough shots for all who wanted them.
The FDA approved the vaccine Fluarix for people 18 years and older. The shots, made in Germany by a subsidiary of GlaxoSmithKline, have been available in other countries for years.
A spokesman said the company expects to supply 8 million doses to the U.S. market this flu season, at a price comparable to other flu shots. Flu vaccine typically costs less than $20 a dose.
The government hasn't yet predicted just how much flu vaccine the nation will have this fall, after last year's surprise shortage when British regulators shut down a U.S. supplier, Chiron Corp., because of the discovery of contaminated vaccine.
Sanofi-Pasteur, the nation's leading flu shot provider, plans to produce 50 million to 60 million doses for this fall. Another 3 million doses of a nasal-spray vaccine, MedImmune Inc.'s FluMist, are also expected to be available. That vaccine is for use only by healthy people.
"Having more manufacturers of influenza vaccine licensed in the U.S., and having more vaccine dosages, is critical to public health," said Health and Human Services Secretary Mike Leavitt.
Last year, the U.S. government expected a record 100 million flu vaccines to be available, but Chiron was unable to ship 46 million doses because of the contamination. Fears of shortages led to the vaccine being rationed to children, the elderly and others considered at serious risk if they caught the flu, but some vaccines ultimately were not used.
Wednesday's FDA clearance licenses Glaxo to sell its vaccine in the United States for the first time. Last year, it provided a few million doses to the United States on an emergency basis, but they were not used.
The FDA granted Glaxo the license under a special fast-track approval system that will require the company to do follow up studies verifying that the level of protective antibodies its brand of shots produced in recipients does translate into true flu protection.
Also Wednesday, Chiron announced that it had passed one step — an inspection of its factory in Britain — toward restoring FDA approval to sell flu shots here, but it still has more work to do with no guarantee of clearance before flu vaccination begins in October.
Because of the uncertainty about supplies, federal health officials already are planning to urge the elderly and others most at risk from the flu to be the first vaccinated. High-risk people include those 65 or older, nursing home residents, anyone with a chronic condition such as heart or lung disease, babies and toddlers ages 6-23 months, pregnant women and health providers who care for high-risk patients.
If there's enough of vaccine, the Centers for Disease Control and Prevention will tell healthier people to get the shots as well.