Researchers delivered a double dose of good news Sunday in the fight against flu: successful tests of what could become the first new flu medicine in a decade, and the strongest evidence yet that such drugs save lives, not just shorten illness.

A single intravenous dose of the experimental drug peramivir cleared up flu symptoms as well as five days of Tamiflu pills did, a large study in Asia found. An IV treatment is badly needed because many sick people can’t swallow pills and because illness hinders the body’s ability to absorb oral medicines.

Several other studies showed the value of treatment with Tamiflu. In one study of hundreds of people stricken with bird flu around the world, half of those given Tamiflu survived, while nearly 90 percent of those not given flu medicines died. Other research showed Tamiflu improved survival from regular seasonal flu, too.

“There has been an accumulation of evidence over time that the antiviral drugs can save lives,” and the new studies confirm that hope, said Nancy Cox, flu chief at the U.S. Centers for Disease Control and Prevention.

Results were reported Sunday at an American Society for Microbiology conference in California. It is the first big meeting of infectious disease specialists since the new H1N1 swine flu emerged in April.

In the meantime, as students across the country return to schools, reports are streaming in that swine flu is causing havoc in children and young adults. Swine flu now accounts for most flu cases in the United States. More than 1 million Americans have been infected and nearly 600 have died from it, the CDC estimates.

Also Sunday, Health and Human Services Secretary Kathleen Sebelius said that the nation’s first round of swine flu shots could begin sooner than expected, with some vaccine available as early as the first week of October.

Sebelius told ABC’s “This Week” that she is confident the vaccine will be available early enough to beat the peak of the expected flu season this fall.

The possibility of early shots follows encouraging news from last week about the swine flu vaccine. Researchers have discovered that one dose instead of two could be enough for healthy adults, and protection could begin once vaccinated within 10 days instead of three weeks.

“That’s great, which means we’ll have a lot more vaccine,” Sebelius said.