In the event of a bird flu pandemic more vaccine will be ready

Oct 24 2007

The World Health Organization (WHO) has revised it's estimate of how much bird flu vaccine could be available were a pandemic scenario to unfold.

The WHO says recent scientific advances and increased vaccine supply means that more pandemic influenza vaccine courses will be accessible in the future.

Last year the WHO, together with vaccine manufacturers, stated that about 100 million courses of pandemic influenza vaccine based on the H5N1 avian influenza strain could be produced immediately with standard technology.

Because of a more efficient formula that figure has now been revised to 4.5 billion pandemic immunization courses per year in 2010.

WHO's Director for vaccine research, Dr. Marie-Paule Kieny, says although the revised figures demonstrate significant progress, they are still far from the 6.7 billion immunization courses that would be needed in a six month period to protect the whole world.

Dr. Kieny says drug makers such as Novartis, GlaxoSmithKline and Sanofi Pasteur are now able to produce 565 million doses of seasonal flu vaccines a year, as against 350 million in 2006.

But Dr. Kieny warns that accelerated preparedness activities backed by political impetus and financial support, must continue, in order to bridge the substantial gap which still exists between supply and demand.

According to the International Federation of Pharmaceutical Manufacturers & Associations, this year manufacturers have been able to increase the production capacity of trivalent (three viral strains) seasonal influenza vaccines to an estimated 565 million doses, from 350 million doses produced in 2006.

Experts say the yearly production capacity for seasonal influenza vaccine is expected to rise to 1 billion doses in 2010, provided corresponding demand exists.

The amount of antigen that has to be used to make each dose of the vaccine is linked to vaccine production capacity.

Seasonal vaccines provide immunity against three strains of virus and pandemic shots only one, so many more doses of the anti-bird flu jabs could be produced in the same facilities; manufacturers would be able to deliver around 4.5 billion pandemic influenza vaccine courses as such a vaccine would need about eight times less antigen, the substance that stimulates an immune response.

A recent scientific discovery, reported last week, reduces the amount of antigen used to produce pandemic influenza vaccines by using water-in-oil substances that enhance the immune response.

Health experts agree the world is overdue for an influenza pandemic and though uncertainty exists over which strain will trigger it, the main suspect is the H5N1 bird flu virus that has already killed 203 people in 11 countries since 2003.

As many as 60 percent of those infected have died from the virus but as yet it has not mutated into a form that is easily transferred between humans.

Kieny says that much more needed to be done to reach the goal of having enough vaccine to serve the world's 6.7 billion people in the event of a pandemic, which could occur in several waves around the globe.

Each year seasonal flu causes severe illness in 3 to 5 million people every year, in addition to 250,000-500,000 deaths, mainly among the elderly and chronically ill.