No country will have adequate supplies of bird flu vaccine for several weeks if influenza, caused by the H5N1 bird flue virus, breaks out in a pandemic form. |
It will take between three and six months for the companies to start commercial production of an effective vaccine following the emergence of the pandemic virus, cautions the World Health Organisation (WHO) in a note on the current status of vaccine research. |
Vaccines are considered the first line of defence for stemming excess mortality and morbidity caused by a pandemic, by building up immunity against the disease pathogen. (Drugs, on the other hand, treat the illness after the infection sets in). |
The commercial production of an effective vaccine cannot begin prior to the emergence of a pandemic. This is because the vaccine needs to be a close match to the actual pandemic virus and for this the precise form of the circulating virus needs to be characterised, the WHO note points out. |
"Current production capacity estimated at around 300 million doses of trivalent seasonal vaccine per year falls for below the demand that will arise during a pandemic", the WHO says. |
It also cautions that, on current output trends, most developing countries will have no access to a vaccine during the first wave of a pandemic. The manufacturing capacity for influenza vaccine is overwhelmingly concentrated in Europe and North America. |
The WHO also maintains that at present, little knowledge exists to guide formulation of an influenza vaccine that is both effective and economises on the use of antigen (component of the vaccine that provides immunity against the disease). |
However, clinical trials are under way to test different formulations and it is hoped that these trials will provide some answers. The apex body is encouraging companies to test vaccine formulations that include an adjuvant (substance that boosts the immune response) that can help provide protection at lower intake of antigen. |
Around 10 countries have domestic vaccine manufacturers. Several of these are presently working on the development of a pandemic vaccine. Some of these are reported to have reached the stage of clinical trials. The WHO hopes to start receiving the results of concluded clinical trials from next month. |
"But if a pandemic were to begin within the next few months, no company would be ready to immediately commence commercial production", the WHO has categorically stated. |
The WHO has been constantly monitoring the evolution of the most dreaded H5N1 virus of avian influenza ever since its initial infection of humans was reported in Hong Kong in 1997. It has a network of specialised influenza laboratories which prepare the prototype vaccine strain that is being provided to the industry as the "seed" for vaccine development. |