Monovalent Oral Polio Vaccine Shows Improved Efficacy
Monovalent vaccine is more effective than standard trivalent vaccine in study conducted in India
FRIDAY, April 13 (HealthDay News) -- A monovalent oral vaccine against type 1 poliovirus introduced in 2005 is almost three times as effective as the standard trivalent vaccine in preventing persistent poliovirus transmission in India, one of the last remaining infected countries, according to a report published online April 12 in The Lancet.
Nicholas C. Grassly, D.Phil., from Imperial College London in the United Kingdom, and colleagues examined the efficacy of monovalent oral type 1 poliovirus vaccine (mOPV1) by looking at 2,076 matched case-control pairs of confirmed poliomyelitis caused by type 1 wild poliovirus and non-polio flaccid paralysis in the state of Uttar Pradesh in India. The efficacy was determined by estimating vaccine coverage from data on cases of non-polio paralysis. Comparisons were made with the standard trivalent poliovirus vaccine.
The researchers estimated that the mOPV1 vaccine had a protective efficacy of 30 percent against type 1 paralytic disease compared with 11 percent for the trivalent vaccine. At the end of 2006, after the mOPV1 vaccine became available, an estimated 76 percent to 82 percent of children under 2 years old were protected by vaccination compared with 59 percent at the end of 2004, before mOPV1 was available.
"The demonstration of superior effectiveness of mOPV vaccine adds to the evidence that termination of wild poliovirus transmission is technically feasible, given enough time, continued funding, political stability, and continued political support in the affected areas of the world," state the authors of an accompanying editorial.