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High-dose bird flu vaccine trial fails

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  • High-dose bird flu vaccine trial fails

    High-dose bird flu vaccine trial fails

    By Julie Robotham
    February 18, 2006

    AUSTRALIA'S highly anticipated bird flu vaccine trial has produced immune protection against the virus in only a small minority of the 400 volunteers who received it, disappointing experts and throwing out estimates of how long it would take to vaccinate citizens in the event of pandemic.
    Andrew Cuthbertson, the chief scientific officer of manufacturer CSL Ltd, said about half of those who received the highest dose in the trial - two 15-microgram shots with a booster substance added - had an immune response comparable to that for regular human flu shots.
    But those who received single or smaller doses of the H5N1 bird flu antigen, and those whose shots did not contain the immune-boosting adjuvant, had a lesser response that was below the threshold for licensing human flu vaccines.
    Dr Cuthbertson conceded the result was disappointing, but said it was positive that the company had produced a safe vaccine with no adverse reactions beyond soreness at the injection site.

    He also emphasised the comparison with ordinary human flu shots was "conservative", and if H5N1 mutated to readily infect humans the required dose might be quite different. "No one on earth now knows the relationship between [test] results and protection," he said. "Does a certain antibody level stop you dying, or getting sick, or have any effect at all?"
    CSL will now begin a larger trial that will include children and the elderly and will focus on higher doses still: double shots of 30 and 45 micrograms each.
    Experts believe there is a one in 10 chance H5N1, which has swept across bird populations in Asia and caused 91 human deaths, could evolve to spread directly between people and trigger a pandemic. Concern has mounted in recent weeks as the virus has been isolated in birds in Africa, which is poorly equipped to cull infected birds.
    Worldwide hopes had been pinned on the CSL trial, because more people could be protected more quickly if a low dose had worked. The lowest dose previously confirmed effective was two 30-microgram injections, in research by CSL's rival, the French company Sanofi-Pasteur.
    CSL previously estimated it could produce enough vaccine to immunise all Australians within six months, but that was based on two injections, each containing 7.5 micrograms of antigen.
    The new findings mean more than double that dose might be required to achieve robust protection against any human strain of H5N1 - potentially blowing out production time to more than a year based on factory capacity.

    Alternatively, the Government could choose to distribute a lower dose vaccine while recognising it might afford only partial protection, Dr Cuthbertson said. He said the results opened the way for the Government to stockpile antigen ahead of time, but a spokeswoman for the federal Health Department, Kay McNiece, said yesterday it was too early to consider placing a contract based on the preliminary research.
    The co-director of the National Centre for Immunisation Research and Surveillance, Robert Booy, said the results indicated "it's going to take longer than the best-case estimates without a doubt," to produce enough vaccine to immunise all Australians.
    That meant other tactics such as border protection, quarantine and the use of protective clothing would need to come to the fore in national pandemic planning, Professor Booy said.
    He welcomed the plan to test the vaccine in children, saying they were a potentially significant source of infection in the community. As well, it was possible children might receive good levels of protection at lower vaccine doses because of their more responsive immune systems.

  • #2
    Re: High-dose bird flu vaccine trial fails

    More like 2 years to 2 1/2 years for Australia to produce the vax for the strain that appears at their shores.

    Anyone here think the virus will wait around and not evolve?

    The insanity is in the failure to construct in AU at least 6 vax plants, now.