WHO eggs on vaccine yield effort

       The World Health Organisation will work with Thai medical experts to overcome their problems in making a vaccine for type-A (H1N1) flu.
       The Government Pharmaceutical Organisation has reported a disappointingly low yield from vaccine viruses grown in hen eggs.
       WHO representative Maureen Birmingham said vaccine experts in Geneva and experts from the Public Health Ministry and GPO would discuss what to do next in a teleconference.
       Dr Birmingham said she was confident the seed virus used for making the vaccine was of good quality and the low vaccine virus yields reported so far could be overcome.
       The GPO said few viruses had grown in the eggs, which were imported from Germany.
       The low yield means the GPO's clinical trial of the vaccine might now be delayed for another two months. The agency had planned to start the first trial on Sept 4.
       Technical experts in Geneva who were incubating viruses in eggs have reported yields of half or less what the manufacturers obtained when they made a vaccine against seasonal flu viruses.
       New seed strains have been made in the hope of increasing the vaccine yield.
       The vaccine virus is injected into thousands of eggs. The eggs are then incubated for two to three days during which time the virus multiplies.
       Despite the low yield rate, GPO board chairman Vichai Chokewiwat said he hoped the next batch of viruses, to be harvested on Aug 28, would produce a better result.
       He said the clinical trial might be postponed for only two weeks.
       The agency is also waiting for a recommendation from the US Food and Drug Administration on whether Thai eggs are safe enough for growing vaccine viruses. The WHO approved only German eggs for live-attenuated vaccine production at a pilot plant here.