Bird Flu Alarm

Understanding Avian Influenza



It takes a while for the flu vaccine to build up a protective level of antibodies. What if you neglected to get your flu shot and now an epidemic has arrived?

Flu Mist
On 17 June 2003, the U. S. Food and Drug Administration (FDA) approved FluMist® - a live-virus vaccine that is given as a spray up the nose.

The viruses have been weakened so that they do not cause illness, but are able to replicate in the relatively cool tissues of the nasopharynx where they can induce an immune response. Presumably this is tilted towards IgA production, a better defense against infection by inhaled viruses than blood-borne IgG antibodies.

All three currently-circulating strains of flu (H1N1, H3N2, and B) are included. As new strains appear, they can be substituted.

At present, this new vaccine is not approved for children younger than five (who might love to avoid a needle) and adults over 50. People with immunodeficiency (e.g., ) should also be cautious about taking it.

Amantadine and Remantadine
These drugs block the shift in pH that the flu virion (A strains only; it doesn't work for B) needs in order to get its contents into the cytosol.


These drugs block the neuraminidase and thus inhibit the release and spread of fresh virions. Spraying zanamivir into the nose or inhaling it shortens the duration of disease symptoms by one to three days.

Why so Few Drugs

Antibiotics are of absolutely no value against the flu virus. However, they are often given to patients to combat the secondary bacterial infections that occur and that are usually the main cause of serious illness and death. The mechanisms by which amantadine and zanamivir work provide a clue.

There are far fewer anti-viral drugs than antibacterial drugs because so much of the virus life cycle is dependent on the machinery of its host. There are many agents that could kill off the virus, but they would kill off host cell as well. So the goal is to find drugs that target molecular machinery unique to the virus. The more we learn about these molecular details, the better the chance for developing a successful new drug.

Cautionary note, it has been officially echoed that "there is no vaccine currently available for the bird and one will take months to create, be tested and mass produced. And with any luck the virus will not mutate once again within that time.

This is nothing less than a race to the death!

Understanding Avian Influenza