Bird flu vaccine offers limited protection but 'better than nothing'

Feb 28 2007

Despite evidence it will not protect most people, a panel of health advisers have recommended that the Food and Drug Administration (FDA) in the United States approve the first vaccine against bird flu.

The director of the FDA's office of vaccine research and review, Norman Baylor, admits that the vaccine which is manufactured by Sanofi-Aventis, had failed to meet existing FDA standards of 70 percent effectiveness in people tested.

But he says there are numerous vaccines in development which are potentially better than this vaccine, which is seen as an interim measure.

The vaccine has been developed to protect against the H5N1 virus, and the outside panel agreed both standards of safety and efficacy had been met.

The vaccine is already being stockpiled for interim use to protect emergency workers and others in a pandemic until better vaccines become available.

Clinical trials showed the two-shot course appears to provide protection to just 45 percent of adults who received the highest dose, lower than was first expected.

Regular flu shots, as a rule protect 75 percent to 90 percent of vaccinated adults younger than 65.

The U.S. government awarded the French company a contract of $372 million and intends to buy and stockpile enough bird flu vaccine for 20 million people, including emergency and health care workers.

The vaccine will not be sold commercially.

Studies are already underway into the use of immune boosters, called adjuvants, to try to improve the effectiveness of the H5N1 vaccine.

Adjuvants also might shrink the needed dose for a pandemic vaccine so it is similar to what is used in seasonal shots.

Scientists also are studying the development of cell-based vaccines, which would be faster to produce in an outbreak of deadly flu than are current egg-based vaccines.

Since it first reappeared in 2003 in Asia, the H5N1 strain of bird flu has killed at least 167 people worldwide, and has been responsible one way or another for the death of millions of birds.

The worry is that it may mutate and develop into a form that easily spreads from person to person, triggering a worldwide pandemic.