Proven efficacy for new polio vaccine

A new vaccine to prevent type-1 polio is three times as effective as the standard vaccine, according to new research.

Electron micrograph of polio virus particles

The study, by researchers at Imperial College London, found that each dose of the new monovalent oral poliovirus vaccine, known as mOPV1, protected 30% of susceptible children in northern India against paralytic poliomyelitis. The standard trivalent vaccine in the same setting protected just 11% of children per dose.

Dr Nick Grassly, lead author of the study from the department of Infectious Disease Epidemiology, said: “Our research shows that the clinical efficacy of the monovalent vaccine in this difficult setting is about three times that of the trivalent vaccine against type 1. This is important, since a child has an 80% chance of protection after 5 doses of this new vaccine. With the trivalent vaccine 14 doses were needed to reach this level of protection.

“The global eradication of type 2 wild poliovirus in 1999 - probably due to the greater efficacy of the trivalent vaccine against this type - proves the concept that with a more efficacious vaccine, wild poliovirus can be eradicated,” he added.

The efficacy of trivalent vaccines – which target polio types 1, 2 and 3 -  can be diminished because different strains of poliovirus interfere with one another inside the body, sometimes producing immunity to one strain but not another. Monovalent vaccines do not incur problems with interference between vaccine strains because they include just one of the three strains. mOPV1 targets type 1 polio, the most prevalent of the three strains of the disease.

Oliver Rosenbauer, of the Global Polio Eradication Initiative at the World Health Oragnisation, said: “By using a monovalent polio vaccine you get mush better protection faster for fewer doses than with the traditional vaccine. For global success, we need to finish the job quickly.”
The research has been published in The Lancet.