Current News
25 June 2010NEJM/ Imperial College London
New insight into tackling vaccine-derived poliovirus
A vaccine-derived strain of poliovirus that has spread in recent years is serious but it can be tackled with an existing vaccine. For a new study published in the New England Journal of Medicine researchers looked at the largest recorded outbreak of a cVDPV to date, which began to circulate in Nigeria in 2005. The authors examined data from 278 children paralysed by this cVDPV, and compared them with children paralysed by wild-type poliovirus in the country.
Their analysis showed that this serotype 2 cVDPV is as easily transmitted and likely to cause severe disease as wild-type poliovirus of the same serotype.The study also shows that vaccination with trivalent OPV, one of the main types of vaccine currently used to combat polio, is highly effective in preventing paralysis by this serotype 2 cVDPV. The research shows that it is even more effective against cVDPV than against the wild-type polioviruses that are currently circulating, which can also be targeted with a different vaccine.
Helen Jenkins, the lead author of the study from the Medical Research Council Centre for Outbreak Analysis and Modelling at Imperial College London, said: "Our research shows that vaccine-derived polioviruses must be taken seriously and that we have the right tools to tackle them. We've had a lot of success against polio in the past and we're optimistic that ultimately we should be able to eradicate it completely.The researchers also say that should wild-type poliovirus be eradicated, routine vaccination with oral polio vaccines will need to cease, in order to prevent further vaccine-derived strains of the virus from emerging.
Polio was virtually wiped out by the early 2000s following a major vaccination drive by the Global Polio Eradication Initiative, but since then the number of cases of paralysis reported has plateaued, remaining roughly constant at between one and two thousand each year from 2003 to 2009, dropping only recently in 2010. The first reported polio outbreak resulting from a circulating vaccine-derived poliovirus, known as a cVDPV, occurred in Hispaniola in 2000. Prior to the actual study, there was little evidence available about the severity and potential impact of this kind of poliovirus.
Jenkins H.E., Aylward R.B., Gasasira A., Christl A., Donnelly C.A., Mwanza M., Corander J.,Garnier S., Chauvin C., Abanida E., Pate M.A., Adu F., Baba M., Grassly N.C.: Implications of a Circulating Vaccine-Derived Poliovirus in Nigeria. New England Journal of Medicine (in press)
