U.S. Swine Flu Vaccine Trials Se...(ms are more effective. The two-dose ...),Health

The two-dose regimens will be given three weeks apart. Two manufacturers, Sanofi Pasteur and CSL Biotherapies, produced the vaccines.

If these trials seem safe, the vaccines will also be tested in children aged 6 months to 17 years, according to the NIAID statement.

"The response to the vaccine may vary in different age groups," said Dr. Karen Kotloff, a professor of pediatrics and lead investigator at the Vaccine and Treatment Evaluation Unit at the University of Maryland, one of the medical centers chosen for the trials. In a statement released by the university, Kotloff explained that age could make a difference in vaccine response because "young people have not seen a flu virus like this before," whereas older Americans might have been exposed to H1N1 type strains in the past.

Additional trials will look at concurrent administration of the swine flu vaccine with regular, seasonal vaccine.

"It makes sense to test the combined swine flu and seasonal flu vaccines because there are some populations in whom both vaccines are indicated," Treanor said. "It would certainly be easier to give them at the same time but these trials are mostly focused on making sure they don't interfere with each other in some way and that they still get a good response."

Besides the University of Maryland School of Medicine, other centers taking part in the trials include the University of Iowa; St. Louis University; Baylor College of Medicine in Houston; Children's Hospital Medical Center, Cincinnati; Emory University in Atlanta, Group Health Cooperative, Seattle; and Vanderbilt University in Nashville, officials said.

In Australia, Adelaide-based drug manufacturer Vaxine initiated trials Monday with 300 participants, while Melbourne's CSL has 240 people in its seven-month study. Australia had 14,703 confirmed cases of swine flu as of Wednesday, and at least 41 deaths, according to the Associ
'/>"/>