The World Health Organization (WHO) predicts that the global capacity to manufacture human vaccine against the deadly H5N1 strain of bird flu is higher than it estimated last year. WHO representatives told the press in Geneva yesterday that scientific advances and increases in production capability have caused vaccine experts to revise their projections of the numbers of vaccines that could be available.

In spring last year, the WHO, together with vaccine producers, estimated that about 100 million human vaccines for H5N1 bird flu could be made available almost immediately with the technology available. However, the latest estimate is that global capacity to produce the vaccine will rise to a figure of 4.5 billion courses per year in 2010.

WHO Director of the Initiative for Vaccine Research, Dr Marie-Paule Kieny told the press that:

“With influenza vaccine production capacity on the rise, we are beginning to be in a much better position vis-à-vis the threat of an influenza pandemic.”

But Kieny went on to say that although the progress was significant:

“It is still far from the 6.7 billion immunization courses that would be needed in a six month period to protect the whole world.”

Political impetus and financial support was still very much needed to back “accelerated preparedness activities” and bridge the “substantial gap” between supply and demand, she said.

Figures from the International Federation of Pharmaceutical Manufacturers & Association suggest that manufacturers have increased this year’s production capacity for trivalent (three viral strains) seasonal influenza vaccines to an estimated 565 million doses, over 60 per cent more than last year’s production of 350 million doses.

Experts in vaccine supply estimate that yearly capacity for seasonal flu vaccines will go up to 1 billion doses in 2010, as long as demand persists, reported the WHO.

This corresponds to a capability to deliver about 4.5 billion pandemic flu vaccines because this requires a lower concentration of antigen to stimulate an immune response compared to seasonal flu vaccine. Recent scientific discoveries reveal that by using water-in-oil substances in pandemic vaccines it is possible to reduce the amount of antigen that is needed to produce the necessary immune response.

An independent, international committee of 10 members,The WHO’s Global Action Plan Advisory Group, met to discuss options to step up vaccine production. This could be achieved by continuing to promote seasonal influenza vaccine programmes, supporting producers to keep capacity beyond seasonal demand and helping them to change from producing inactivated vaccines to live attenuated vaccines, should a pandemic occur.

This last option, because of the higher yields possible with live attenuated vaccine production methods, could, said the Advisory Group, close the supply-demand gap by 2012, and attain the goal of having enough vaccine to treat a global population within 6 months of a pandemic outbreak being declared.

The deadly strain of H5N1 bird flu virus is presently only infectious from bird to human. However, it has a high rate of fatality and many experts believe it is only a matter of time before the strain mutates into a form where it can pass easily from human to human and break out into a global pandemic with the potential to cause tens of millions of deaths worldwide.

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Written by: Catharine Paddock