Avian Flu Infections in Humans Prompt New Investigation

Robert Belshe, MD, from Saint Louis University Center for Vaccine Development

 

In 1918, nearly 40 million people died in a flu pandemic. Three such pandemics have occurred during the last 100 years. When a new strain of flu infects people, the infection can spread around the world quickly. This is what could potentially happen with some new human flu viruses that come from bird flu viruses.

Recently, some strains of bird flu viruses have infected people in Asia, said Robert Belshe, MD, director of the Center for Vaccine Development at Saint Louis University School of Medicine. There is concern these new strains could cause a pandemic, but they are not infecting people in the United States at this time. Rather than wait for that possibility to occur, the National Institutes of Health (NIH) is testing avian influenza vaccines.

The National Institute of Allergy and Infectious Diseases (NIAID), part of the NIH, has tested a new H5N1 avian influenza vaccine in healthy adults at clinical sites across the country. Now that safety data are available from the first adult study, NIAID plans to test this vaccine in other populations. As part of this plan, Saint Louis University will be testing an investigational vaccine in children ages 2 to 9, a population that is especially vulnerable to acquiring influenza.

Saint Louis University will conduct a research study using a killed flu virus vaccine for the bird flu virus, known as A/H5N1. This experimental vaccine was made the same way as regular flu vaccine that is given to people every year before flu season. In this study, researchers are evaluating the investigational vaccines safety and ability to stimulate antibodies, part of the bodys proteins that fight infections, in children. Study participants may receive two or three doses of the investigational vaccine. There is also a chance that participants will receive a placebo injection of saltwater instead of the investigational flu vaccine.

One hundred twenty children will be vaccinated nationwide. Researchers in St. Louis are looking for healthy children ages 2 to 9 to participate in this study. Children who were previously vaccinated against the flu this flu season are eligible for the study.

A January 2005 editorial in the New England Journal of Medicine warned that the virus that causes avian flu, which killed 32 people in eight Asian countries in 2004, had become more dangerous, and had increased the number of animals besides birds it could kill. A separate article in this journal also described the first probable person-to-person transmission of bird flu, from an 11-year-old girl to her mother and aunt; both mother and child died.

Belshe said the last worldwide flu pandemic was in 1968 (the Hong Kong flu), and most of the commonly circulating flu strains of today are genetically related to that outbreak. Before the Hong Kong pandemic there was the 1957 Asia pandemic, and before that, the influenza pandemic of 1918 occurred.

In the last century weve had three pandemics, Belshe said. The concern is that a new virus will again emerge and cause a new pandemic. We need to be ready. Once it starts, it could spread worldwide quickly because of air travel. You cant close the borders to flu. The only protection we have against flu are vaccines for prevention and antiviral drugs for prevention or treatment.

Source: Saint Louis University Health Sciences Center