The U.S. Food and Drug Administration has approved Fluarix Quadrivalent to immunize children age 3 and older and adults against flu virus subtypes A and B contained in the vaccine.

It is the first intramuscular vaccine to protect against four influenza strains. Three-strain flu vaccines currently administered help protect against the two most common A virus strains and the B strain expected to be predominant in a given year, the company said.

Since 2000, however, two B virus strains have circulated to varying degrees each season, meaning patients infected with the B virus not contained in the vaccine were not immunized.

Fluarix Quadrivalent helps protect against the two A strains and adds coverage against a second B strain, the company said.

Three-strain vaccines "have helped protect millions of people against flu, but in six of the last 11 flu seasons, the predominant circulating influenza B strain was not the strain that public health authorities selected," said Dr. Leonard Friedland, head of clinical development and medical affairs for Glaxo's North American vaccines program.

"Fluarix Quadrivalent will help protect individuals against both B strains and from a public-health standpoint, can help decrease the burden of disease."

Glaxo said it will make the vaccine available in time for the 2013-14 flu season and plans to fulfill orders for its trivalent, or three-strain, vaccines. Healthcare providers traditionally order flu vaccines about a year in advance of each flu season.

Fluarix Quadrivalent is not currently approved or licensed in any country outside of the United States.

(Reporting By Toni Clarke; Editing by Maureen Bavdek)

• A Permanent Economic Emergency