Human Tests of Experimental Bird Flu Vaccine Begin

BETHESDA, Maryland, March 25, 2005 (ENS) - Federal health officials are moving quickly towards development of a vaccine to prevent bird flu in humans. Fast-track recruitment has begun for a trial to investigate the safety and effectiveness of a vaccine against the H5N1 strain of avian influenza, the director of the National Institute of Allergy and Infectious Diseases (NIAID) said Wednesday.

University medical facilities in New York, Maryland and California are seeking a total of 450 healthy adults to receive the trial vaccine.

"While there have been relatively few cases worldwide of H5N1 avian influenza infection in humans, the public health community is concerned that the virus will develop the capability of efficiently spreading from human to human and thus create a risk for a worldwide pandemic," says Dr. Anthony Fauci, director of NIAID, which is part of the National Institutes of Health.

Fauci

Dr. Anthony Fauci, M.D. is director of the National Institute of Allergy and Infectious Diseases, Department of Heath and Human Services. (Photo courtesy U.S. State Department)
Sanofi pasteur, the vaccines business of the Sanofi-Aventis Group based in France, was awarded a contract by NIAID to manufacture the vaccine in May 2004. Sanofi pasteur manufactured the experimental vaccine, which is an inactivated vaccine made from an H5N1 virus isolated in Southeast Asia in 2004.

The company is building a state of the art vaccine production facility at its U.S. site in Swiftwater, Pennsylvania.

In addition to the previous contract awarded to Sanofi pasteur, in May 2004 NIAID also awarded a contract to Chiron Corporation of Emeryville, California, to produce H5N1 vaccine for clinical trials.

Both companies already manufacture inactivated influenza virus vaccines that are licensed for use during annual influenza seasons.

"NIAID has supported research on H5N1, the strain responsible for this deadly form of avian influenza, since 1997 when the first cases in humans were reported," Fauci said. "The initiation of this vaccine trial marks a key advance in our efforts to prepare to respond to an avian flu pandemic."

This Phase I trial will test the vaccine's safety and ability to generate an immune response in 450 healthy adults aged 18 to 64. If the vaccine is found to be safe in adults, there are plans to test it in other populations, such as elderly people and children.

The H5N1 avian influenza leads to severe disease in both birds and humans. Between January 2004 and March 11, 2005, there were 69 confirmed cases of and 46 deaths from H5N1 infection in humans reported to the World Health Organization.

To date, there has been a small number of cases where human-to-human transmission of the virus may have occurred. However, public health experts fear that the virus may evolve into one that is more easily transmitted between people. If this were to happen, a worldwide pandemic could follow.

Influenza pandemics are global outbreaks that emerge infrequently and unpredictably and involve strains of virus to which humans have little or no immunity. H5N1 is one such flu virus strain. The last influenza pandemic swept the globe in 1968; many public health officials believe the world is overdue for another one.

The clinical facilities now enrolling vaccine test volunteers are:

The clinical sites are part of the NIAID-sponsored Vaccine and Treatment Evaluation Units.

Aventis Pasteur and Chiron will each produce between 8,000 and 10,000 doses of the trial vaccine made through established techniques in which the virus is grown in eggs and then inactivated and further purified before being formulated into vaccines. The use of established techniques to develop the investigational vaccines will help to promote rapid licensing of commercial pandemic vaccines in the event of a pandemic outbreak.

chickens

These chickens died suddenly of avian influenza in 2004 on a farm in Bangla Bali, Indonesia. (Photo by Ian Douglas courtesy FAO)
Avian influenza viruses do not normally infect species other than birds and pigs, according to the World Health Organization. The first documented infection of humans with an avian influenza virus occurred in Hong Kong in 1997, when the H5N1 strain caused severe respiratory disease in 18 humans, of whom six died. The infection of humans coincided with an epidemic of highly pathogenic avian influenza, caused by the same strain, in Hong Kong’s poultry population.

Investigation of that outbreak determined that close contact with live infected poultry was the source of human infection. Studies at the genetic level determined that the virus had jumped directly from birds to humans. Limited transmission to health care workers occurred, but did not cause severe disease.

Rapid destruction – within three days – of Hong Kong’s entire poultry population, estimated at around 1.5 million birds, reduced opportunities for further direct transmission to humans, and may have averted a pandemic.

That event alarmed public health authorities, as it marked the first time that an avian influenza virus was transmitted directly to humans and caused severe illness with high mortality. Alarm mounted again in February 2003, when an outbreak of H5N1 avian influenza in Hong Kong caused two cases and one death in members of a family who had recently travelled to southern China.

An epidemic of highly pathogenic avian influenza caused by H5N1, which began in mid-December 2003 in the Republic of Korea and spread to other Asian countries, was of great concern to health officials. Millions of chickens were killed to control the spread of the disease.

In 2004, the H5N1 virus caused illness in 44 people in Thailand and Vietnam, 32 of whom died. Researchers worry that this deadly flu strain is becoming endemic in Asia.

NIAID's website on influenza research is at: http://www2.niaid.nih.gov/Newsroom/FocusOn/Flu04/