evidence: Introduction of Inactivated Poliovirus Vaccine and Switch from Trivalent to Bivalent Oral Poliovirus Vaccine - Worldwide, 2013-2016 [...] To reduce the risk for cVDPV2 outbreaks and to facilitate responses to outbreaks that do occur, injectable trivalent inactivated poliovirus vaccine (IPV) is being introduced into routine immunization schedules in all countries. As of June 24, 2015, 90 (46%) of 194 World Health Organization (WHO) member states were using IPV, 102 (53%) had established dates for the introduction of IPV, and two (1%) intended to introduce IPV in 2015 but had not set dates for doing so. In addition to IPV introduction in all countries, careful synchronization of the switch from tOPV to bOPV will be needed within and across all 156 countries currently using tOPV. This report summarizes progress in introducing IPV and preparations for the switch from tOPV to bOPV. [...] Polio endgame: the global introduction of inactivated polio vaccine.Expert Rev Vaccines. 2015 May;14(5):749-62. doi: 10.1586/14760584.2015.1001750. Epub 2015 Jan 19. Expert Rev Vaccines. PMID: 25597843 Review.