Image copyright Getty Images Image caption The virus does not spread from person to person, according to the CDC
The United States Food and Drug Administration (FDA) has approved a new form of boosters for the H1N1 influenza virus, or swine flu.
The new drug is aimed at the over-65s but is also available for people aged between 18 and 64.
It is also authorised for people who had had the virus recently.
The approval comes just three weeks after the FDA cleared a new version of another flu drug.
Currently, there are three drugs available for those who have been infected with swine flu: Sanofi’s Oseltamivir, Fluconazole and Avamivir.
But the FDA said the new drug works differently.
Image copyright Getty Images Image caption The new drug increases the body’s levels of protective antibodies when a person gets swine flu
“Up to 70% more immune cells are present in the swine flu vaccine booster than in the current vaccine,” the FDA said in a statement.
Sara Federgruen, head of the influenza division at the FDA, said the drug “improves the effectiveness of the current seasonal vaccine”.
There is no new vaccine available this year.