Journal of Infectious Diseases
http://www.journals.uchicago.edu/toc/jid/current
Volume 205 Issue 2 January 15, 2012

Editorial Commentaries
Stephen L. Cochi and Robert W. Linkins
The Final Phase of Polio Eradication: New Vaccines and Complex Choices
J Infect Dis. (2012) 205(2): 169-171 doi:10.1093/infdis/jir727

Extract
The Global Polio Eradication Initiative (GPEI) made rapid progress after its launch by the World Health Assembly in 1988, reducing polio cases by more than 99% from an estimated 350 000 in 1988 to 719 cases in 2000. However, further progress toward eradicating polio stalled after 2000 in a handful of tropical endemic countries, and the international spread of the virus from these endemic areas led to recurrent outbreaks in previously polio-free countries. One factor related to the stalled progress was the well-documented lower immunogenicity and effectiveness in tropical developing countries of oral poliovirus vaccine (OPV) [1,  2], so attention focused on developing and licensing monovalent type 1 and type 3 vaccines to improve the effectiveness of vaccination by avoiding cross-interference between the 3 serotypes that occurs following vaccination with the traditional trivalent OPV (tOPV). This issue of the Journal contains the most recent in a series of 3 clinical trials in 2 African (Egypt, South Africa) countries and 1  Asian (India) country, demonstrating the superior type-specific immunogenicity in developing countries of monovalent oral poliovirus vaccines (mOPVs), as compared with tOPV [3–6]. In particular, the 3 trials demonstrate the superior immune responses of monovalent OPV type 1 (mOPV1) and type 3 (mOPV3) compared with tOPV, either following 1 dose of vaccine given to newborn infants (in Egypt and South Africa), or 2 doses given at birth and 1 month of age (in India).

Monovalent or bivalent (types 1 and 3) OPV can overcome some of the limitations of tOPV, including the interference among the 3 Sabin strains. Because the type-2 component of tOPV replicates more efficiently and is considerably more immunogenic than the other components …