WHO flu vaccine forecast an underestimate

The forecast that 4.5 billion doses of pandemic influenza vaccine could be produced by 2010 is an underestimate, according to GlaxoSmithKline.

The World Health Organisation (WHO) announced yesterday it was increasing its projections for global production capacity of the vaccine following recent scientific advances.

But UK drug giant GSK told in-PharmaTechnologist.com the WHO prediction was a gross underestimate and that a production capacity of 12 billion doses was a more accurate prediction.

"The key reason for that is adjuvant technology", a GSK spokeswoman said.

Adding an adjuvant to a vaccine has the ability to increase the immune response while reducing the amount of antigen needed to elicit the response.

GSK is currently working on an undisclosed adjuvant that is being used in H5N1 vaccine clinical trials.

Results so far, suggest just 3.8mg of antigen is required to produce an immune response which reflects 80 per cent efficacy.

In comparison, seasonal flu vaccines, because they are trivalent, made up of three vaccine strains, require 45mg of antigen.

GSK's adjuvanted vaccine has also shown in trials to induce cross-protection of different H5N1 strains.

Novartis is another company developing an adjuvant.

MF59 has been included in several studies where it was found it might reduce the amount of antigen needed for an immune response and potentially provide cross-protection against changing flu strains.

In January this year, both Novartis and GSK were awarded contracts with the US government to develop their adjuvant technologies for pandemic influenza.

The GSK spokeswoman said all vaccines would require the adjuvant to be able to reach the 12 billion dose mark and suggested GSK could supply the adjuvant to other manufacturers of pandemic influenza vaccine.

According to the WHO, 6.7 billion immunization courses would be required in a six-month period to protect the whole world.

Currently, about 200,000 people are hospitalized every year with influenza in the US alone. An additional 36,000 people die annually from the seasonal disease.

If a pandemic occurred without a vaccine, the WHO estimates that at least 50 million people could die.

"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," WHO director of the initiative for vaccine research Dr Marie-Paule Kieny said in a statement.

"Accelerated preparedness activities must continue, backed by political impetus and financial support, to further bridge the still substantial gap between supply and demand."

Most manufacturers developing pandemic influenza vaccine provide seasonal vaccine as well.

Currently, an estimated 565 million doses of seasonal flu vaccine will be supplied this year, up from 350 million in 2006. According to experts working in the field, the yearly production capacity for seasonal influenza vaccine is expected to rise to one billion doses in 2010.

But should a pandemic hit, much of the manufacturing capacity used for seasonal vaccines would be converted for the production of pandemic vaccines.

As this would have implications on seasonal influenza vaccine supply, many companies are working with governments and the WHO to stockpile pre-pandemic vaccine.

Meanwhile, advances are continually being made into ways of producing influenza vaccines that do not require the lengthy six-month time-frame involved with current egg-based techniques.

Earlier this year, GSK was awarded $274m to develop cell-culture technology to speed the development of vaccines, and to scale-up cell culture manufacturing capability at its Pennsylvania site.

Sanofi-Aventis is the only pharmaceutical company to have an H5N1 vaccine approved in the US, but the French company's vaccine does not contain an adjuvant.

Spokesmen from Novartis and Sanofi were unavailable for comment at time of publishing.