New Methods Could Speed Production of Flu...(do not elicit as strong an immune respon...),Health

"Virus-like particles look just like a live virus, but they are hollow shells without a genome inside, and they cannot reproduce," Ross said. "Because they look like the virus, they evoke a more robust immune response against the real thing."

Inhaled, mist-based flu vaccines can also elicit a strong immune response, but they are associated with an increased risk of side effects, because they are made with live, attenuated virus, the release noted.

Still, there is disagreement over who should be vaccinated and for what flu viruses, Ross said.

"There is a debate in the influenza community about priming the human population for potential pandemic strains such as H5N1 or 1918," Ross said. "Some researchers advocate adding these strains to the annual flu vaccine. They might not match the next pandemic flu strain exactly, but could provide some protection."

Others contend that it's premature and too costly to vaccinate people against a virus that may never emerge, he said.

More information

The CDC has more on flu vaccines.

-- Jennifer Thomas

SOURCE: American Society for Microbiology, news release, May 18, 2009