TRIAL OF EXPERIMENTAL AVIAN INFLUENZA VACCINE

Influenza Vaccine

Fast-track recruitment has begun for a trial to investigate the safety of a vaccine against the H5N1 strain of avian influenza, the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), announced today.

Sites in Rochester, NY, Baltimore and Los Angeles will enroll a total of 450 healthy adults. The clinical sites are part of the NIAID-sponsored Vaccine and Treatment Evaluation Units (VTEU). While there have been relatively few cases worldwide of H5N1 avian influenza infection in humans, the public health community is concerned that the H5N1 strain of avian influenza virus will develop the capability of efficiently spreading from human to human and thus create a risk for a worldwide pandemic.

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. The initiation of this vaccine trial marks a key advance in our efforts to prepare to respond to an avian influenza pandemic.

Sanofi pasteur, Swiftwater, PA, manufactured the trial vaccine, which is an inactivated vaccine made from an H5N1 virus isolated in Southeast Asia in 2004. Sanofi pasteur, formerly Aventis Pasteur, was awarded a contract by NIAID to manufacture the H5N1 vaccine in May 2004.

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

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 Avian Influenza virus strain. The last influenza pandemic swept the globe in 1968; many public health officials believe the world is overdue for another one.

Avian Influenza Infection in Humans

Although avian influenza A viruses usually do not infect humans, more than 100 confirmed cases of human infection with avian influenza viruses have been reported since 1997. For example, the World Health Organization (WHO) maintains situation updates and cumulative reports of human cases of avian influenza A (H5N1). Most cases of avian influenza infection in humans are thought to have resulted from direct contact with infected poultry or contaminated surfaces. However, there is still a lot to learn about how different subtypes and strains of avian influenza virus might affect humans. For example, it is not known how the distinction between low pathogenic and highly pathogenic strains might impact the health risk to humans. (For more information, see �Low Pathogenic versus Highly Pathogenic Avian Influenza Viruses� on the CDC Influenza Viruses Web page.

Because of concerns about the potential for more widespread infection in the human population, public health authorities closely monitor outbreaks of human illness associated with avian influenza. To date, human infections with avian influenza A viruses detected since 1997 have not resulted in sustained human-to-human transmission. However, because influenza A viruses have the potential to change and gain the ability to spread easily between people, monitoring for human infection and person-to-person transmission is important.