By Darren Schuettler BANGKOK, Dec 6 (Reuters) - A vaccine against the killer H5N1 bird flu virus could be licensed for human use in a year, but when to use it is becoming a "tricky issue", a senior World Health Organisation official said on Wednesday. Drug companies are racing to find a cure for the avian influenza virus which has killed 154 people since 2003 and fanned fears of a global human pandemic. At least a dozen manufacturers have clinical trials underway or planned. "We can expect that a year from now there would be vaccines against H5N1 influenza strains that would be licensed for human use," Marie-Paule Kieny, head of the WHO's Initiative for Vaccine Research, told reporters on the final day of a WHO vaccine conference in Bangkok. Health experts say vaccines work well when they match the circulating strain of flu. The H5N1 strain has not evolved yet into a form that passes easily between humans, but studies suggest some vaccines might help protect people from death if a pandemic strain does emerge. Several countries have ordered or are negotiating to stockpile pre-pandemic H5N1 vaccines, which some experts recommend to immunise health care workers, firefighters and other essential staff before a pandemic breaks out. David Salisbury, director of immunisation at Britain's Department of Health, told the conference it would take 4-6 months for the first vaccine doses to emerge from factories, and up to a year to produce enough for the recommended two doses. "During this time, at least the first pandemic wave will be over, and the second and third waves, should they occur, may also be over before significant numbers of individuals can be vaccinated," he said. Salisbury said some data on vaccines had shown that "even if poorly matched against the pandemic strain, they may play a valuable role in minimising disease, reducing transmission and even aborting a pandemic". PRODUCTION PROBLEMS Kieny said the WHO did not yet have an official position on pre-pandemic vaccination, which she called a "tricky issue". "We need to take into consideration that immunising part of your population, especially groups on the front line to combat the pandemic, might be a good benefit," she said. "But you have to weigh that against the risk of immunising against a pandemic that is not there," she said, referring to the 1976 swine flu scare in the United States. That year, millions of Americans were vaccinated against swine flu after an outbreak at a U.S army base triggered fears of a wider pandemic. It never occurred and the vaccine was blamed for a rise in cases of a rare neurological illness. WHO officials said several projects were now underway to boost production capacity for vaccines to protect against bird flu and other viruses with pandemic potential. The U.N. health agency launched a plan in October to increase global flu vaccine capacity, which is expected to rise to 780 million doses by 2009 under current expansion plans, still far short of what would be needed to fight a global pandemic. The strategy calls on governments to increase normal flu vaccination campaigns to encourage companies to raise capacity. Drug makers could also be paid to keep capacity idle for pandemic vaccines. It also urges study of more potent vaccines to reduce the number of recommended doses to one from two. The plan could cost $3-$10 billion over the next decade. "None of these strategies will be able to fill the gap in the immediate short term but, starting now, first results may be seen in three to five years," the WHO's Alejandro Costa said.
