LONDON (Reuters) - A bird flu vaccine for humans, which requires only a very low dose of active ingredient, has proved effective in clinical tests, its maker GlaxoSmithKline Plc said on Wednesday.
The promising result means Europe's biggest pharmaceuticals group is on track to start making the vaccine in commercial quantities by the end of the year.
Glaxo believes its H5N1 vaccine will work more efficiently than rival ones in development because of the proprietary adjuvant used in its manufacture. Adjuvants are additives put into vaccines that boost the immune system and make it respond more efficiently.
A key challenge in the race to produce a vaccine for millions of people around the world is how to make the maximum number of shots from the minimum amount of antigen, or active ingredient.
The H5N1 strain of avian influenza has spread rapidly out of Asia and has killed more than 130 people who have come into close contact with infected birds.
Experts fear it could trigger a pandemic, a global epidemic of flu that could kill millions, if it acquires the ability to pass easily from human to human.
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Before we start dancing in the streets, there are a few caveats to this story.
First, the vaccine has only been tested in a small sample of subjects. The antibody levels detected, which demonstrate immunity, was suffiicient in 80% of subjects. Which is about what most flu vaccines provide.
Second, this vaccine is based on an older clade of the virus. How well it will work, if at all, against a mutated virus is anybody's guess. The hope is, it will help reduce the mortality rate, but it may not prevent infection.
Third, the world production capability has been repeatedly stated to be between 300 million and 500 million doses. Since this immunization requires two shots, presumably 30 days apart, the number of people who could be innoculated runs between 150 million and 250 million a year.
This is still good news. Until now, without adjuvants, it's taken 12 x's this much antigen to get this kind of response. It puts us closer to having a vaccine, at least in limited quantities.
The problems of production, logistics, and distribution still remain.
