Advances in researches of serotype 2 novel oral polio vaccine

In April 2016, the Global Polio Eradication Initiative (GPEI) adjusted its polio vaccination strategy, converting trivalent oral polio vaccine (tOPV) into bivalent oral polio vaccine (bOPV), and withdrawing type 2 oral polio vaccine (OPV2) globally. However, after the withdrawal of OPV2, there were many outbreaks of type-2 circulating vaccine-derived poliovirus (cVDPV2) in Asia and Africa. In order to eradicate poliovirus completely, GPEI launched the research and development of the novel serotype 2 oral polio vaccine (nOPV2) in 2010 and considering whether it is necessary to reuse OPV. This paper summarizes the epidemiological situation of cVDPV2 before and after OPV2's withdrawal, the related factors affecting the reuse of OPV and the related research progress of nOPV2.