Avian flu is an imminent threat to health

Avian flu is an imminent threat to health and well-being. For birds. In Asia and Eastern Europe.

That reality is easily missed in the face of warnings from government officials and public health experts of an impending global pandemic that could take millions of lives, devastate economies and require militarily-enforced quarantines.

The highly virulent strain of influenza that is devastating bird populations in Asia is arousing concern among medical experts because the disease has proven to be transmissible from infected birds to humans with lethal consequences - 60 of the 117 confirmed cases in humans have been fatal, according the World Health Organization. But nearly every human case has resulted from direct contact with an infected bird, and at this point the virus does not transmit easily from human to human. Experts worry that the bird flu virus could mutate in a way that would make it more easily transmissible from person to person.

Efforts to contain bird flu range from monitoring bird populations to expediting research to develop a vaccine for broad use should the disease begin to spread among humans. John Treanor, a professor of medicine at the University of Rochester and lead investigator in a National Institutes of Health-sponsored trial of a prospective avian flu vaccine, addressed questions.

Q. Recent reporting on the avian flu seems to suggest that a human pandemic is inevitable. Is that the case?

A. I think there is a real possibility that we will have a pandemic of flu due to one of these bird flu viruses. There are a lot of things we don't know about the epidemiology of flu and how flu pandemics get started. I think it is definitely something that we need to take seriously and worry about and be prepared for, but I don't know that it is inevitable.

Q. Your work is aimed at developing a vaccine. How would such a vaccine be used?

A. We are testing a prototype vaccine that is designed to be very similar to a regular flu shot but that contains the components of bird flu. And we're looking at that vaccine to see that it's safe and also to determine the best dose to use and to look at what the immune response to the vaccine actually is.

If it were to work out, it would be given prophylactically in much the same way as the regular flu shot. The specific target groups would depend on what the supply was and on what was judged to be the risk.

Q. Would the high-risk groups that get the regular flu shot first also be first in line?

A. I think it would probably be very similar, but perhaps it would be a little bit more shaded toward health-care workers and first-responder types than the way we use the current vaccine. We currently recommend that all health care workers with direct patient contact receive vaccine, but we're not so focused on support personnel who don't have direct patient-care contact. I could imagine a scenario with a pandemic where you might want to also include those people.

Q. Would there be a similar problems of not being able to produce enough vaccine?

A. The vaccine that we're testing is designed to use a process that is as close to the regular flu shot as possible because that is a much easier vaccine to approve by regulatory authorities. They can view that as just being a change in the strains and not a radically new approach to vaccination.

Q. Will the regular flu shot provide any protection against avian flu?

A. No. But the regular flu shot will protect you against regular flu, and that might actually be more important, at least this year, because no one wants to get regular flu.

Q. What makes this strain of avian flu more virulent than others?

A. No one knows.Pandemics happen when a new virus arises that is different in its outer coating from viruses that people have previously been exposed to. When you get the flu, or when you get vaccinated, you make an immune response against the outer coat of the virus. That allows you to be protected against future infections with viruses that have the same kind of outer coat.

Influenza viruses change a little every year.... They undergo a process called antigenic drift that does allow them to reinfect people, but those reinfections tend to be much more mild. Mild, of course, is a relative term. Flu is responsible for deaths and hospitalizations, but (its impact is) ameliorated to a certain extent by the experience that a person has had with related flu viruses.

When a pandemic occurs, the central thing that happens is that the virus has a completely different outer coat, and that allows very rapid spread in a population that has no underlying immunity. In 1957, we had a pandemic where a new virus, an H2 virus, showed up in a population that had previously only experienced an H1. And in 1968, we had a pandemic when a new virus, an H3, showed up in a population that had only experienced H1 and H2.


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