One-Dose Swine Flu Vaccine Looks Promising

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Hopeful news in the battle against the H1N1 swine flu emerged Thursday as European and Chinese researchers said they have developed swine flu vaccines that work with one dose, rather than two, potentially increasing the supply available for distribution.

Novartis, the Swiss drug maker, found that in a British trial of 100 people between 18 and 50 years old, participants had adequate protection two weeks after just one injection, the Associated Press reported.

In China, a swine flu vaccine was approved on Thursday, which also works with one dose, according to its maker, Sinovac Biotech Ltd.

"The pilot results are encouraging," Andrin Oswald, CEO of Novartis Vaccines and Diagnostics, said in a statement. "This is important information for public health authorities who prepare for vaccination in the coming months with limited vaccine supply."

Scientists previously thought two doses would be necessary, which could have contributed to a vaccine shortage. The World Health Organization declared swine flu a pandemic in June, and last month it said efforts to create an effective vaccine were progressing slowly, which could limit supplies this fall, when a resurgence of swine flu is expected.

Although encouraged, health experts said additional trials of both vaccines are needed to determine if a single dose is enough. How these developments will affect the worldwide supply is still unclear, because Novartis' vaccine relies on cell culture, while most flu vaccines use chicken eggs.

The Novartis formula, like most European vaccines, also uses adjuvants, a chemical component intended to make the vaccine more efficient. Neither the United States nor Canada has licensed flu vaccines with adjuvants, and limited information exists on how they affect pregnant women and children, two groups considered at high risk in a pandemic, the AP said.

The Sinovac vaccine and some others being tested in China and the United States do not use adjuvants.