A new vaccine against polio will be used for the first time today in polio immunization campaigns in Afghanistan. The bivalent oral polio vaccine (bOPV), recommended by the Advisory Committee on Poliomyelitis Eradication, the global technical advisory body of the Global Polio Eradication Initiative as a critical tool to eradicate polio, can provide the optimal concurrent protection needed by young children against both surviving serotypes (types 1 and 3) of the paralysing virus. This will vastly simplify the logistics of vaccination in the conflict-affected parts of this country. This sub-national immunization campaign, from 15-17 December, will deliver bOPV to 2.8 million children under five in the Southern, South-Eastern and Eastern Regions of Afghanistan.
Of the three wild polioviruses (known as types 1, 2 and 3), type 2 has not been seen anywhere in the world since 1999. This achievement led to the development of monovalent vaccines, which provide protection against a single type with greater efficacy than the traditional trivalent vaccine. To determine whether a bivalent vaccine could effectively protect children living in areas where both types circulate, a clinical field trial completed in June 2009 compared bOPV with the existing vaccines. For both types 1 and 3 polio, bOPV was found to be at least 30% more effective than the trivalent vaccine and almost as good as the monovalent vaccines, yet in a package that could deliver both at once.
The bOPV allows countries to simplify vaccine logistics and to optimize protection using a mix of the available polio vaccines according to local needs. In southern Afghanistan, where access to children can be limited depending on the security situation, using bOPV helps maximise the impact of each contact with a child.
Most of Afghanistan is polio-free: 28 out of the 31 children paralysed by polio this year come from 13 highly insecure districts (of 329 districts in the country). In 2009, polio eradication efforts in Afghanistan have focused on improving operations and creating a safe environment for vaccination teams. Nongovernmental agencies have been contracted and local leaders involved to ensure that parties in conflict are approached, safe passage for vaccinators assured and children reached. Due to such preparations and strengthened supervision and staffing, the proportion of the nearly 1.2 million children under five years old in the Southern Region who could not be reached was reduced from more than 20% in early 2009, down to 5% during the July and September 2009 campaigns. The availability of bOPV multiplies the effect of such improvements. However, in the 13 highest-risk districts of Kandahar and Helmand provinces in the Southern Region, the proportion of children who are still unimmunized is well above 20% – and more than 60% in some areas.
Four countries in the world have never stopped polio transmission – Afghanistan, India, Nigeria and Pakistan. Types 1 and 3 polio circulate in limited parts of all these countries, and the others will follow Afghanistan's lead in using bOPV during the coming months, marking the adoption of a major new tool in the international effort to eradicate polio. While the Global Polio Eradication Initiative, a public-private partnership leading the effort, has reduced the incidence of polio by more than 99% (from an estimated 1000 children affected daily in 1988 to 1483 children in all of 2009 to date) polio still has a foothold in the four endemic countries. The consequences are severe beyond those areas: 16 previously polio-free countries are currently suffering outbreaks following importations of the virus; in four of these, polio transmission has lasted more than a year.
The availability of bOPV is part of a range of new and area-specific tactics in 2009 to reach eradication more quickly. The swift production of the vaccine was the result of extraordinary collaboration between the World Health Organization, UNICEF, vaccine manufacturers and regulatory agencies.
The vaccination campaign in Afghanistan is financed by the Government of Canada. Canada, which assumes presidency of the G8 in 2010, first placed polio on the group's agenda when it last held the presidency in 2002. The G8 is the single-largest donor bloc to polio eradication.
The Global Polio Eradication Initiative is spearheaded by the World Health Organization, Rotary International, the US Centers for Disease Control and Prevention and UNICEF.
