The World Health Organisation is consulting national officials and drug makers this week on whether the threat from the new Influenza A (H1N1) strain is serious enough for large-scale production of a pandemic vaccine to start. The series of consultations, which conclude on Thursday, will form the basis of a recommendation to vaccine manufacturers from the WHO.
This will not be an easy decision for WHO director-general Margaret Chan Fung Fu-chun. The virus is spreading around the world. But, much remains unknown about the nature of the new bug, how infectious it will prove, the severity of the respiratory illness it will cause and the age groups that are most vulnerable.
The confirmed death toll from H1N1 is now more than 50, mainly in Mexico. Yet, between 250,000 and 500,000 people around the world die from seasonal flu every year.
Of the various ways devised by scientists to defend against seasonal and pandemic flu approved so far by health regulators, vaccination is rated the most effective. But vaccine production takes months.
Most vaccines contain a dead or weakened form of a circulating virus, cultivated in chicken eggs, although a small number of companies have been approved to use cell cultures. Either way, the vaccine works by triggering the body's immune system.
If the WHO recommends that drug makers switch to large-scale output of pandemic vaccine at such an early stage in the evolution of the H1N1 strain, will there be enough production capacity left to meet the annual seasonal flu demand of around 500 million doses? These shots are recommended by doctors to ward off flu, particularly among the elderly, disabled, those with chronic medical conditions, and other groups such as pregnant women and health care workers.
Different types of vaccines cannot be produced simultaneously in the same facility for fear of cross-contamination. For some manufacturers with only one plant, switching to pandemic production would mean stopping seasonal output. Still, this may not be a major problem because the WHO has been told by drug companies that they have substantial extra production capacity. The major ones also have multiple plants.
