Study: Single dose of H1N1 flu vaccine may suffice for adults

A single low dose of H1N1 vaccine may be enough to protect adults from the flu virus that has been spreading around the world, new data shows. Researchers in Australia said they tested the H1N1 vaccine in 240 people ages 18 to 64. Half were given a dose of 15 micrograms while the others were given 30 micrograms. After 21 days, blood samples showed that most participants had an immune response of 1 to 40 titers or more, the researchers said.