Experimental Avian Flu Vaccine Effective, U.S. Health Officials Say
An experimental vaccine against a strain of avian flu "appears to be effective" at protecting against infection, "offering the first evidence that any inoculation could provide a powerful weapon against the deadly microbe," federal health officials announced on Saturday, the Washington Post reports. According to the Post, international public health officials are concerned that a strain of avian flu known as H5N1 -- which has spread among birds in Asia and Russia and also has infected more than 100 humans, killing about half of them -- could mutate and begin to spread from human to human, sparking a global pandemic.
In response, U.S. researchers have been working with vaccine makers Chiron and Sanofi Pasteur to develop a vaccine to protect against the strain. The Sanofi Pasteur vaccine, which was the subject of health officials' announcement Saturday, is being tested in 452 healthy adult volunteers under age 65 at the University of Maryland Baltimore, the University of Rochester and the University of California-Los Angeles.
In their announcement on Saturday, U.S. health officials said that the Sanofi Pasteur vaccine, which has been tested in 113 volunteers so far, produced an "immune system response potent enough to neutralize the virus," the Post reports. Given in two doses four weeks apart, the vaccine spurred the volunteers' immune systems to produce antibodies in direct proportion to the dose of the vaccine they received, with the strongest dose producing what is considered an adequate response, according to Anthony Fauci, director of NIH's National Institute of Allergy and Infectious Diseases.
The vaccine now is being tested in other healthy adults, after which it will be tested in additional groups, such as the elderly and children (Stein, Washington Post, 8/7). According to the New York Times, the additional testing is needed to determine the best dose of the vaccine, how many shots people would need to obtain protection from H5N1 and whether the addition of another ingredient could boost the potency of lower doses, thus expanding the number of people who could gain protection from a smaller amount of vaccine.
The U.S. government could decide to release the vaccine under emergency conditions if an H5N1 pandemic occurred before testing was finished, the Times reports (Altman , New York Times, 8/7). Fauci said that during testing the U.S. government will move ahead with plans to purchase doses of the vaccine for the U.S. stockpile.
Health officials acquired two million doses from Sanofi Pasteur to launch the stockpile prior to testing in case the tests were successful (Pace, AP/Las Vegas Sun, 8/7). However, because the initial tests showed that the volunteers required higher-than-normal doses of vaccine to gain protection against H5N1, the existing two million doses might contain enough vaccine to inoculate only 450,000 people.
Sanofi Pasteur executives and health officials said they are working to find a formula that would allow the vaccine to be administered in a single dose but added that a two-dose vaccine is more likely (Wysocki, Wall Street Journal, 8/8).
"This is very good news," Fauci said, adding, "This is the first vaccine that anybody has that has been tested to show that you can actually produce a robust immune response." Fauci said that although the data are "preliminary," they also are "pretty solid." He added, "Having a vaccine in case we had a pandemic flu is a very important part of a comprehensive response to a pandemic" (Washington Post, 8/8).
Fauci said, "We can make a vaccine that induces a powerful response, even though the dose is higher than a standard vaccine. And it is safe" (Wall Street Journal, 8/8).
However, Fauci cautioned that "there are still many, many obstacles to what we would call total preparedness" for a possible flu pandemic (Manning, USA Today, 8/8). Although FDA likely would approve the new vaccine quickly because it would be considered an update to other seasonal flu vaccines, the global vaccine industry lacks the manufacturing capacity to produce the number of doses that might be needed in a pandemic, Fauci said.
He noted that a pandemic could require hundreds of millions of doses of vaccine, adding that the companies that currently produce flu vaccines would not be capable of producing seasonal inoculations and bird flu vaccines simultaneously. Production of bird flu vaccine will not start until mid-September at the earliest, Fauci said (AP/Las Vegas Sun, 8/7).
Even "if every vaccine manufacturer decided to start doing this, we still would not have enough," he warned (USA Today, 8/8).
Michael Osterholm, a vaccine expert at the University of Minnesota, said, "These are very important studies. This is confirmation of what we hoped would be the case. We all had anticipated that two doses were going to work. If it didn't, we would be in trouble."
However, Osterholm added that the international health community remains seriously unprepared to handle a flu pandemic if it occurs, in part because the world's capability to quickly produce and distribute a large amount of vaccine is inadequate. "That's the Achilles' heel of our public heath response. These data are encouraging and supportive, but in the end, a lot of people would be left unvaccinated in the event of a pandemic," he said (Washington Post, 8/7).
HHS Secretary Mike Leavitt said, "It all ties back to capacity. A zero-sum game isn't a happy result. We're spending significant time and effort seeking ways to alter that equation -- new technologies, new capacity and a combination of the two" (Wall Street Journal, 8/8).
Several other newspapers recently examined issues related to avian flu. Summaries of the articles appear below.
CQ HealthBeat: CQ HealthBeat on Thursday examined how Leavitt in recent weeks has focused on preparing for the possibility of a "catastrophic flu pandemic." According to Leavitt, his soon-to-be-released final plan for the U.S. response includes a "tool kit" of five solutions to speed delivery of drugs and vaccines across the nation (CQ HealthBeat, 8/4).
New York Daily News: The Daily News in an editorial on Monday said the announcement of a successful vaccine for H5N1 is "a ray of hope in an otherwise bleak and very dangerous landscape." The Daily News said that a pandemic could be halted but only if "global awareness raising and cooperation start now" and if the U.S. creates a "national plan for dealing with a pandemic, its immediate effects and aftereffects" (New York Daily News, 8/8).
New York Times: An article in the Times on Sunday examined the process through which the Sanofi-Pasteur vaccine was created and tested. The Times reports that the only way scientists would be able to definitively prove the effectiveness of the vaccine is if an epidemic of H5N1 occurs among the public (Altman , New York Times, 8/7).
New York Times: The Times on Monday examined the overall prevention and preparation strategy related to the possibility of a pandemic influenza related to avian flu. According to U.S. health officials, the existence of a vaccine is not enough to prepare for a pandemic, and additional measures, including improved monitoring of influenza activity on a global scale and increased vaccine production activity, are necessary (Altman/Bradsher, New York Times, 8/8).
- Wall Street Journal: The Journal on Monday examined how local and international officials are working to control the spread of avian flu among birds as they struggle to track the migratory habits of infected flocks in China and elsewhere (Zamiska, Wall Street Journal, 8/8).
NPR's "All Things Considered" on Sunday included an interview with Fauci about progress toward an avian flu vaccine (Ludden, "All Things Considered," NPR, 8/7). The complete segment is available online in RealPlayer.
In addition, NPR's "Morning Edition" on Monday included an interview with John Treanor of the University of Rochester and lead investigator for tests of a potential avian flu vaccine (Inskeep, "Morning Edition," NPR, 8/8). The complete segment is available online in RealPlayer.