Vaccine development

Vaccines are considered the first line of defence for reducing the excess morbidity and mortality that invariably accompany pandemics.For several reasons, no country will have adequate supplies of vaccine at the start of a pandemic and for many months thereafter. Large-scale commercial vaccine production is not expected to commence until about three to six months following the emergence of a pandemic virus.Manufacturing capacity for influenza vaccines is overwhelmingly concentrated in Europe and North America. Current production capacity falls far below the demand that will arise during a pandemic.

Constant monitoring

WHO, through its network of specialized influenza laboratories, has constantly monitored the evolution of the H5N1 virus since its initial infection of humans in Hong Kong in 1997.These laboratories prepare the prototype vaccine strain that is being provided to industry as the “seed” for vaccine development. Constant molecular analyses of viruses, conducted by these laboratories, help ensure that work on vaccine development stays on track. This is particularly important in view of mutations in the virus detected during 2005.Around 10 countries have domestic vaccine manufacturers, and several of these are presently working on the development of a pandemic vaccine. Some of these development projects have reached the stage of clinical trials; clinical trials of other candidate vaccines are expected to begin shortly. However, if a pandemic were to begin within the next few months, no company would be ready to move immediately into commercial production.

Commercial vaccine production

As a pandemic vaccine needs to be a close match to the actual pandemic virus, commercial production cannot begin prior to emergence and characterization of the pandemic virus.WHO has, however, encouraged industry and regulatory authorities to develop fast-track procedures for licensing and marketing authorization of a pandemic vaccine, and this has been done.In addition, WHO is using international meetings to urge the international community to find ways to increase manufacturing capacity and ensure that developing countries have access to an effective vaccine at an affordable price. On current trends, however, most developing countries will have no access to a vaccine during the first wave of a pandemic and perhaps throughout its duration.SOURCE: WHO Vaccine research and development