Brazilian boost for bird flu vaccines
Brazilian scientists have developed a modifying agent which could make vaccines for the H5N1 bird flu virus cheaper, more effective, and easier to produce.
The development could help developing countries at the forefront of any bird flu pandemic struggling to access and afford the vaccines and drugs produced and stockpiled by developed countries.
Researchers from the Butantan Institute, based in São Paulo, Brazil, claim that an adjuvant called Monophosphoryl Lipid A (MPLA) was effective in boosting the immune response to strains of Vietnamese and Indonesian avian flu virus in mice.
An adjuvant is a chemical substance that boosts a vaccine's effectiveness by increasing its ability to stimulate the immune system.
According to Isaías Raw, director of the institute, MPLA reduced the amount of antigen — virus protein — needed to cause an immune response to one quarter of that previously required, reducing the cost of vaccine production.
Raw says were a pandemic to occur now, the adjuvant would enable 80–100 million doses of seasonal flu vaccine to be produced by the end of April.
Clinical trials in humans are planned, with results expected at the end 2008.
John Oxford, scientific director of Retroscreen Virology Ltd and professor of virology at UK-based Queen Mary's School of Medicine and Dentistry, said the adjuvant "looks to be a most interesting and practical step forward that will be needed in the face of a pandemic."
He also stressed the importance of increased hygiene and isolation procedures as well as the building a stockpile of antiviral drugs.
Marie-Paule Kieny, director of the World Health Organization (WHO) Initiative for Vaccine Research, cautioned that results were still only available for mice and that it was too early to assess the vaccine's effectiveness in humans.
But she welcomed the development and said the WHO had initiated collaboration with the Butantan Institute on the development of a potential H5N1 influenza vaccine.
According to Raw, use of MPLA could allow Brazil and other developing countries to produce their own vaccines, instead of relying on imports from developed countries.
There are currently no vaccines for H5N1 avian influenza available. The WHO says that vaccines are under development in several countries, but because a vaccine needs to closely match the pandemic virus in circulation, large-scale production would not start until the virus has been properly identified.
Thus, no vaccine is expected to be widely available until several months after the start of a pandemic (see Pandemic flu: fighting an enemy that has yet to exist).
According to the WHO, manufacturers from ten countries are developing prototype vaccines in cell cultures or in eggs inoculated with the virus. More then 40 clinical trials have been completed or are ongoing to test whether the experimental vaccines will work, and to determine the best formulation to boost production capacity.
But the WHO warns that current global production capacity falls far short of the demand expected during a pandemic. It estimates that about 12 billion doses are required to vaccinate the entire world's population with the two-doses needed to protect each person.
Current capacity is estimated at less than 400 million doses per year and this is not expected to exceed 2.3 billion doses per year by 2008–2009.
Countries such as China, India, Thailand and Vietnam are taking steps to ensure that they have their own vaccines available. Last month, Indonesia stirred controversy by signing an exclusive agreement to supply virus samples to a US pharmaceutical company in exchange for technology to manufacture a vaccine (see Indonesia stops sharing bird flu samples).The WHO is helping several developing countries, including Cambodia, Egypt, Laos, Nigeria and Vietnam, to establish their own flu vaccine production facilities.