BOSTONA newer vaccine that targets the most common form of the polio virus works up to four times better than the conventional vaccine that tries to protect against all three types of the crippling disease, researchers said on Wednesday.

The so-called monovalent vaccine may help speed the fight to eradicate polio, US Food and Drug Administration officials Ellie Ehrenfeld and Konstantin Chumakov wrote in a commentary in the New England Journal of Medicine, where two studies on the three-year-old vaccine appear.

One can get much more immunity from the monovalent vaccine than one could with the trivalent doses, Dr Roland Sutter of the World Health Organisation in Geneva, who worked on one of the studies done in Egypt, said in an telephone interview.

Both versions of the vaccine - the newer monovalent and the older trivalent vaccine - are made by French drugmaker Sanofi-Aventis.
Polio spreads through fecal-oral contact and thrives in areas with poor sanitation.

Although eradicated from most of the globe, polio can still be found in northern Nigeria, northern India and along the Pakistan-Afghanistan border. In 2007, 1,310 cases were reported worldwide, according to the US Centers for Disease Control and Prevention.

In a study in Egypt, the vaccines were given at birth to 421 children. The single-target version produced protection in 55.4 percent of newborns, compared to 32.1 among those who got the version targeting three strains of the polio virus.

Four doses are recommended, which ultimately makes them even more effective.

In a study done among more than 2,000 children in Nigeria, a team led by Helen Jenkins of Imperial College London found that a dose of the monovalent vaccine protected against the most common type of polio 67 percent of the time, while use of the conventional vaccine worked in 16 percent of the cases.

The newer vaccine substantially improves the prospects for accelerating elimination in northern Nigeria, Jenkins and colleagues wrote.

In northwestern Nigeria, 55 percent of children have not been properly vaccinated and 21 percent have not received a single dose.

In Nigeria, we now have an effective vaccine to use and weve seen the start of improvements in vaccine uptake. These last pockets of unvaccinated children now need to be reached to achieve elimination in Nigeria, and this in turn will have a dramatic impact on the prospects of worldwide eradication,

Jenkins said in a statement.

Sutter, coordinator of research and product development for WHOs polio eradication program, said the goal is to use the monovalent vaccine to attack the type of polio prevalent in a community, and then use the trivalent vaccine for broader, routine protection.