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Bird Flu Vaccine Falls Short: U.S. Scientists Had Hoped for Better Results From Tests but Say They're Not Giving Up on Research

Posted on: Thursday, 30 March 2006, 06:00 CST

By Delthia Ricks, Newsday, Melville, N.Y.

Mar. 30--A vaccine designed to guard against the avian influenza virus produced a protective response in only slightly more than half of volunteers who got the shots, scientists report in an analysis released today.

Led by Dr. John Treanor of the University of Rochester, the study is the first national test of a vaccine against the strain dubbed H5N1. Public health experts say the pathogen, now a pandemic among birds, could create devastating waves of human influenza if it mutates and jumps species and becomes easily transmitted among people.

Based on a virus that infected a man in Vietnam two years ago, the vaccine is the first in what is expected to be several generations of avian flu shots. Government health officials, nevertheless, are adding the current vaccine to the National Strategic Stockpile at a cost of more than $160 million.

Working with a group of 451 healthy volunteers between the ages of 18 and 64, doctors administered either bird flu shots or shots with a placebo. All volunteers received two vaccinations 28 days apart. Among participants receiving the vaccine, some got higher doses than others to help scientists determine the optimum dose.

Among those who received the highest dosage - 90 micrograms - only 54 percent had a robust response. Effectiveness was determined by measuring the level of infection-fighting antibodies in the blood. Response among people ages 18 to 64 to seasonal flu shots is 75 percent to 90 percent, researchers said yesterday.

"These are lower response rates than one might have expected in regular flu shots in healthy people," Treanor said during a news briefing. No unusual side effects from the vaccine were reported. His study is published in today's New England Journal of Medicine. He said data on the vaccine's effectiveness in elderly people and children is still being analyzed.

Despite the less-than-glowing outcome of the study, Treanor said scientists are not giving up on a bird flu vaccine. "We are, I think, much farther ahead than we would be if we had not started. Now we know that it's going to be a long road."

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said the study's lackluster findings do not spell the end of the nation's bird flu research. He said a second bird flu vaccine based on a virus isolated from an Indonesian patient is being readied for human testing. Results from the current study will aid future vaccine trials, he said.

The study reported today, Fauci added, has provided valuable insights.

"We have a long way to go, so it's a step in the right direction," he said of the current study. "It's doing a number of things: It's paving the way for if and when, and I think it's going to be when, we do have a product that would be much more robust in inducing of an immune response." Based on preliminary results, government health officials were aware as early as last summer that the bird flu vaccine's effectiveness was far below expectations.

Fauci said he and top health officials at the Food and Drug Administration and the Centers for Disease Control and Prevention have discussed the possibility of adding a bird flu component to the seasonal flu vaccine. Nothing is definitive.

So far 186 people worldwide have contracted the infection, mostly from birds; 105 have died.

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Copyright (c) 2006, Newsday, Melville, N.Y.

Distributed by Knight Ridder/Tribune Business News.

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Source: Newsday, Melville, N.Y.

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