The first human trial of a swine flu vaccine made by Swiss drugmaker Novartis started about 10 days ago when a person in Britain received the first shot.
The year-long trial will include 6,000 participants of all ages in Britain, Germany and the United States, drug company spokesman Eric Althoff told the Associated Press. He added that the vaccine will likely be on the market before the trial is completed.
The trial is designed to test the safety of the vaccine and to determine whether people require one or two shots.
"Our assumption is that two doses will be required," Althoff told the AP.
Since swine flu was declared a pandemic by the World Health Organization in June, drug companies have been striving to get their vaccines ready. In July, Australian drugmaker CSL became the first to start testing a swine flu vaccine in humans.
Meanwhile, the World Health Organization reported Tuesday that 338 people died from swine flu in the last week.
The H1N1 virus is now responsible for at least 1,154 deaths since it emerged in Mexico and the United States in April, the AP reported.
Last week, the official WHO death toll was 816.
WHO said Tuesday that laboratory-confirmed cases of the disease have now reached 162,380.