October 12, 2005
Avian flu vaccine against H5N1 strain to be tested on humans next year after promising tests on birds in VietnamTopics: Health Issues
After carrying out successful tests in birds using the flu vaccine against the H5N1 strain, Vietnam, having already suffered 64 human bird flu infections and 21 deaths, will probably carry out tests on humans next year. Monkeys have been successfully vaccinated against the H5N1 strain as well.
The vaccine was developed by Vietnam's National Institute for Hygiene and Epidemiology, which is applying to authorities for trials on humans. It is also seeking approval for the production of vaccines.
Vietnam has vaccinated over 27 million birds in 30 towns and cities, and is carrying out a comprehensive detoxification and disinfection program on poultry farms throughout the country.
The good news of the successful vaccine against the H5N1 strain of avian influenza is tempered by the raising of questions by U.S. researchers about the vaccine's ability to protect large numbers of people.
Among the potential problems: The vaccine dose needs to be much higher than that given for other types of flu, according to Dr. John Treanor, a professor of medicine and associate professor of microbiology and immunology at the University of Rochester School of Medicine and Dentistry.Although the professor makes several important and key points, the fact is that Vietnamese scientists, who have been dealing with the problem long before most U.S. researchers even thought about an emerging H5N1 avian influenza pandemic, have developed a vaccine that has been successfully tested on fowl and monkeys. That means that the world has a shot at beating the dread disease, and although U.S. scientists would like to see improvement- the Vietnamese have proven that it can be done, and soon!
"It seems to be a characteristic of the H5 vaccines that they require a higher dose to illicit an immune response than some other vaccines do. Dose-related immune responses are being tested to get a feeling for what dose would be required. And then we need to see if anything could be done so lower doses could be used," said Treanor, who is the principal investigator of the vaccine tests being done at the University of Rochester.
The problems with a high-dose H5 vaccine are twofold:
First, since people have never been exposed to H5 viruses, a "primer" vaccination would have to be given, then a month later another dose would be required. Because of this two-dose regimen, immunity wouldn't take hold for about six weeks, giving the virus a bigger window to infect even immunized individuals.
Second, the higher dose would place a strain on manufacturers' ability to produce enough vaccine, he said.
It's also not known if the vaccine being tested now would protect against an H5 virus strain that might trigger a flu pandemic.
"The vaccines that have been made would be expected to protect quite well against all the different viruses that have been isolated from people.
Add to this news the fact that U.S. scientists have also developed a vaccine that is now being tested under the auspices of the U.S. Department of Health and Human Services at two or more locations in the U.S., and we have what the world's been waiting with bated breath to hear - we have a good chance of being ready for avian influenza.
However, we can be ready only if we are lucky enough to complete development, successfully test the vaccine in humans with a form of the vaccine that makes sense in the real world(which includes finding the correct dosing, testing, working out manufacturing issues and regulatory approvals), manufacture millions of doses, distribute them to appropriate populations throughout the world, and just as important - H5N1 cooperates by taking it's time completing it's morphing into a deadly strain fully and easily capable of being transmitted between humans, and spreading throughout the world.
That seems like a lot of ifs!
Posted by Richard at October 12, 2005 12:17 PM
Ahh!--Sweet Appeasement. It is no nice to be politically correct. No one is offended. If only everyone were politically correct! What a peaceful world it would be! Then we wouldn't use such offensive words as appeasement. We would use the politically correct word accomodative, or possibly the even more politically correct word--submissive.
Posted by: walt at October 13, 2005 8:31 PM
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- Avian flu vaccine against H5N1 strain to be tested on humans next year after promising tests on birds in Vietnam - Oct 12, 2005