US Food and Drug Administration on Tuesday approved a vaccine designed to protect against the swine flu and hopes to make it available within a month.
The regulator approved the vaccine manufactured by four different drug companies and said the first batches of shots should be available in the US within the next four weeks.
The H1N1 vaccine produces immunity within eight to 10 days of the injection.
The new variant of the influenza virus was discovered in Mexico this spring, prompting fears of a pandemic and researchers have been rushing to develop a vaccine. In the United States 1,380 people have been hospitalized with the virus and 196 had died as of last week, the US Centres for Disease Control said.