SciDev.Net

Nigerian polio awareness poster

WHO/TDR/Crump

Polio could be eradicated within the next year if there is sufficient vaccination and effective surveillance of new cases in the few countries where the virus is still present.

But, as David Heymann, Roland Sutter and Bruce Aylward warn in this article in Nature, although the end of polio is in sight, the decline in polio vaccine research must be reversed to protect against future outbreaks of the disease.

The oral polio vaccine currently in use combats three type of poliovirus. The authors say individual vaccines against each type are needed, as is a new type of vaccine made from inactivated poliovirus.

Since 2000, there have been four outbreaks of polio as a result of new mutations in the virus used in the oral vaccine that have made it virulent and transmissible.

For this reason, say Heymann and colleagues, once the disease is eradicated, immunisation with the oral vaccine must cease.

They add that after eradication, samples of polioviruses must be stored carefully to prevent laboratory accidents such as the ones that led to recent human infections by the viruses that cause smallpox and SARS (severe acute respiratory syndrome).

But the authors stress that in addition to producing stockpiles of new vaccines — an estimated 750 million of each type are needed — maintaining the capacity to produce them will be crucial in future outbreaks

Link to full article in Nature