New egg-free flu vaccine called promising for those with egg allergy

SAN DIEGO, April 2 - Austrian researchers have developed a unique flu vaccine that is made without egg proteins, which can trigger rare but potentially fatal allergic reactions in some people. "The development represents the newest and most successful approach to influenza vaccine development in 50 years," says Otfried Kistner, Ph.D.

Kistner, a virologist with Baxter Hyland Immuno in Orth/Donau, Austria, and director of the research project, described the vaccine today at the 221st national meeting of the American Chemical Society, the world's largest scientific society.

Although at least two other manufacturers are testing egg-free flu vaccines, Kistner notes that only his company is using cells that have previously been accepted by regulatory authorities in the United States and Europe for human vaccine production.

According to the Austrian scientists, their new manufacturing technique is faster than methods that require chicken eggs, which can be in short supply during a large outbreak. As a result, the technique is expected to lessen the likelihood of flu vaccine shortages like those in the United States last year.

Phase I, II and III clinical trials were done in the United Kingdom, Austria and Poland with more than 2,500 volunteers. They were divided into two age groups: 18-59, and 60 and above. The studies showed that the new vaccine was effective in inducing specific antibodies against influenza, an indication that the vaccine will protect against infection.

"This does not mean that (conventional) vaccines are bad," says Kistner. "The benefit of vaccination is much greater than the risk of allergic reaction. The point of our vaccine is to improve it and minimize the risks which may appear."

Among the older patients who received the new vaccine, significantly fewer adverse effects were observed compared to those who received conventional vaccines. In the younger group, no significant differences in adverse effects were observed. Adverse effects were typically mild, including reddening of the skin and swelling.

Although no serious health-related events were reported in clinical trials, the new vaccine will continue to undergo safety evaluations each year, says Kistner. The vaccine is expected to be available to consumers in Europe as early as next year, he adds.

The new technique developed by Kistner and his associates uses a cell line originally derived from kidney cells of the African green monkey. The cell line has a demonstrated safety record in medical applications and is the only cell line currently licensed for the production of vaccines for human use, according to Kistner.

Some viruses are difficult to grow in eggs, which leads to delays in production. Growing the virus in the new cell culture provides manufacturers with the potential to grow such viruses more quickly than in eggs.

The new, cell-based vaccine has an additional benefit: It is produced without thimerosal, a mercury-based preservative that is used to kill bacteria. The chemical is often used in the production of egg-based vaccines, but U.S. and European officials are concerned that the preservative may present potential health risks, including possible allergic reactions.

The virus in a flu vaccine is chemically inactivated, but its presence stimulates the body to generate antibodies to fight off invading influenza strains. The Centers for Disease Control and Prevention (CDC) creates a new vaccine each year based on the likelihood that a new viral strain will occur.

Influenza is a respiratory infection that contributes to 20,000 deaths in the United States each year. At greatest risk are infants, the elderly and people with certain chronic conditions such as diabetes.

Flu season typically lasts from November to March, according to the CDC. The agency recommends that people get vaccinated six to eight weeks before flu season begins to prevent or reduce the severity of infection

The paper on this research, BIOT 42, will be presented at 9 a.m., Monday, April 2, at the San Diego Convention Center, Room 16A, during the symposium, "Advances in Vaccine Development."

Otfried Kistner, Ph.D., is director of the virology department at Baxter Hyland Immuno in Orth/Donau, Austria.

Click here to search for papers.