Birdflu vaccine successful on monkeys

Mar 10 2005

A bird flu vaccine for humans could be only months away since the success of a vaccine on monkeys in Vietnam, researchers hope to have a vaccine ready for testing in humans later this year.

Vietnam, the country hardest hit by the virus which has killed 47 people in Asia and wiped out many millions of poultry, has already had 14 deaths from the bird flu virus in the latest outbreak that began in December.

In early February three monkeys were injected with a vaccine based on weakened H5N1 bird flu virus; three weeks later the monkeys were healthy and had produced anti-bodies. The process was repeated in the monkeys and the results are expected in the next two weeks, says Nguyen Tran Hien, director of the National Institute of Hygiene and Epidemiology. They hope to start tests in September on a small group of volunteers, says Hoang Thuy Nguyen, head of the vaccine research group.Once the results of the repeated injection were known several steps have to be undertaken to ensure the safety of the vaccine before testing it on humans, probably members of his group.

The next tests ideally should include the exposure of the vaccinated monkeys to bird-flu infected chickens, but they are not able to conduct that type of test at present as Vietnam does not have a laboratory that is designed for such tests on animals. Close cooperation with the World Health Organization is needed to help local researchers challenge the virus by exposing the monkeys to infected poultry.

The Thai government is considering a request that a U.S. developed vaccine be tested on people in Thailand, which is also suffering a new bird flu outbreak although it has not reported any human infections since October.

A decision will not be reached until the Public Health Ministry's Medical Science Department have considered all the possible outcomes of testing a bird flu vaccine on humans.

Experts last month expressed the fear that the effectiveness of a vaccine against a versatile and resilient virus if it mutated into a form that could transfer between humans, would be limited. If it does mutate into that form, it is feared a pandemic would be triggerd with a capacity to kill millions of people in a world population with no immunity to it.

The poultry virus has killed one man and infected three - including a man and his younger sister - in northern Vietnam this month, although fewer outbreaks have been detected in poultry. All these cases have clinical factors related to slaughtering and eating poultry, says Health Minister Tran Thi Trung Chien, and there is not as yet any evidence of human-to-human transmission. A Cambodian woman who died in southern Vietnam in January, might have caught it from her younger brother, whose body was cremated before it could be tested for the virus.

Almost all the Asian victims - 34 Vietnamese, 12 Thais and the Cambodian - have caught it from infected poultry. Bird flu kills more than 70 percent of those known to have been infected, but doctors say victims can be saved if they are diagnosed early.