Bird Flu, Revisited

By: Jean Johnson for Body1

Baxter International, Inc. allayed fears of a pandemic by reporting that an early trial of its bird flu vaccine showed promise this past fall. The vaccine was manufactured using cell-based techniques that allow the production of considerably larger quantities than does the current egg-based approach that requires months of cultivation. It is effective against avian influenza A, or the H5 N1 virus. The 270 participants in the trial from Singapore and Austria tolerated the vaccine well, reporting only side effects typical of flu vaccines: soreness, headaches, and fatigue.

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The following information on poultry, eggs, and bird flu is adapted from the Centers for Disease Control and Prevention: You cannot get avian influenza from properly handled and cooked poultry and eggs. Even if poultry and eggs were to be contaminated with the virus, proper cooking would kill it. Cook eggs until whites and yolks are firm. Be sure to wash your hands with soap and warm water for at least 20 seconds before and after handling raw poultry and eggs, as you would normally. Clean cutting boards and other utensils with soap and hot water to keep raw poultry from contaminating other foods. Use a food thermometer to make sure you cook poultry to a temperature of at least 165 degrees Fahrenheit.

“This is the first clinical demonstration that a candidate H5N1 or bird flu virus vaccine can induce antibodies that neutralize widely divergent strains of H5N1,” said Noel Barrett, vice president of global research and development for Baxter’s vaccines business.

Avian influenza is an infection that occurs naturally in birds. While wild birds worldwide usually do not get sick, they carry the highly contagious virus in their intestines. In turn they can transmit avian influenza to domesticated birds like chickens, ducks, and turkeys, all of which can grow exceedingly sick and even die. Most cases of avian influenza infection in humans have resulted from contact with infected poultry.

“The risk from avian influenza is generally low to most people, because the viruses do not usually infect humans. However, confirmed cases of human infection from several subtypes of avian influenza infection have been reported since 1997,” states the Centers for Disease Control (CDC).

The World Health Organizations states that there have been over 250 cases of bird flu reported in humans since 2003. Of the 250 people stricken, 148 have died. According to the CDC, “In general, H5N1 remains a very rare disease in people. The H5N1 virus does not infect humans easily, and if a person is infected, it is very difficult for the virus to spread to another person.” But as the press made clear, the fear has been that the virus will change and be able to infect and spread among humans. Because our immune systems are not prepared for this foreign virus, an influenza pandemic (worldwide outbreak of disease) could begin.

Current Status of Vaccines

Baxter International’s promising work with H5N1 has the company poised for a second trial of the vaccine, with results potentially available by the end of 2007. In addition to Baxter, other large manufacturers are scrambling to develop immunizations against the dreaded bird flu.

GlaxoSmithKline, Europe’s largest drug maker, is working on an egg-based vaccine that could be ready for mass production as early as this year. Similarly, the French company Sanofi-Aventis is trying to beat the clock. Over a year ago, Sanofi-Aventis received a $97 million contract by the U.S. Health and Human Services Department to develop a cell-based method of flu vaccine. The cell-based method is preferred over egg-based because is can shave a month off the six months it takes for egg-based vaccines to develop. Sanofi's cell-based vaccine production is in the pre-clinical phase.

While Sanofi is the first company to be awarded a U.S. government contract for developing a new method of vaccine production, other companies are exploring faster methods of making vaccines effective against bird flu. The Swiss drug maker, Roche, projects that its non-egg-based vaccine will be available in 2008. And Hemispherx Biopharma, a U.S. company in Philadelphia, is also working on a cell-based vaccine.

Assessment of the Current Situation

Bird flu continues to spread in Asia and parts of Europe, the Near East, and Africa. According to the CDC, the virus is “not expected to diminish significantly in the short term. It is likely that H5N1 infection among birds has become endemic in certain areas and that human infections resulting from direct contact with infected poultry and/or wild birds will continue to occur.” They do add that person-to-person spread has been rare and limited up until this point.

One study found that ducks infected with H5N1 virus are increasingly able to carry and pass the virus without showing symptoms of flu. This, of course, increases the chances that ducks will transmit disease to other birds and potentially humans. “The avian influenza A (H5N1) virus that emerged in Asia in 2003 continues to evolve and may adapt so that other mammals may be susceptible to infection as well.”

Although bird flu pandemic concerns are real, it is encouraging to hear that despite the fact that research and production takes time, companies are making headway in vaccine research. Everyone is relieved that thus far the virus is not spreading too fast, and it appears that we have the time needed to develop vaccines.

Last updated: 02-Apr-07