Progress Toward Polio Eradication — Worldwide, January 2018–March 2020

Progress Toward Poliovirus Containment Implementation — Worldwide, 2019–2020

“…The Global Polio Eradication Initiative has achieved its progress through extensive use of trivalent oral poliovirus vaccine (tOPV, which consists of live, attenuated Sabin vaccine strain types 1, 2, and 3). Despite the substantial advancement toward eradication attained using this vaccine, in areas with low population immunity, prolonged transmission of Sabin vaccine virus can lead to viral mutations that result in development of neurovirulent vaccine-derived polioviruses (VDPVs) (1). Outbreaks can result from VDPVs that are transmitted in a community and are known as circulating VDPVs (cVDPVs).…”

“…PV2 disease immunity in the community was to be provided by high coverage with tOPV before the switch as well as a recommended single dose of injectable inactivated polio vaccine (IPV) to help protect against paralysis; however, suboptimal vaccination coverage and IPV manufacturing shortages have led to substantial PV2 immunity gaps in many countries (4). Since the switch, many countries, particularly in Africa, have experienced cVDPV2 outbreaks (1). To combat these outbreaks, vaccination responses with monovalent OPV2 (mOPV2) have been implemented in approximately two dozen countries.…”

“…Since 1988, when World Health Organization (WHO) Member States and partners launched the Global Polio Eradication Initiative, the number of wild poliovirus (WPV) cases has declined from 350,000 in 125 countries to 176 in only two countries in 2019 (1). The Global Commission for the Certification of Poliomyelitis Eradication (GCC) declared two of the three WPV types, type 2 (WPV2) and type 3 (WPV3), eradicated globally in 2015 and 2019, respectively (1). Wild poliovirus type 1 (WPV1) remains endemic in Afghanistan and Pakistan (1).…”

“…The Global Commission for the Certification of Poliomyelitis Eradication (GCC) declared two of the three WPV types, type 2 (WPV2) and type 3 (WPV3), eradicated globally in 2015 and 2019, respectively (1). Wild poliovirus type 1 (WPV1) remains endemic in Afghanistan and Pakistan (1). Containment under strict biorisk management measures is vital to prevent reintroduction of eradicated polioviruses into communities from poliovirus facilities.…”

Viruses That Can and Cannot Coexist With Humans and the Future of SARS-CoV-2

“…(3) vaccination coverage should be high enough to achieve herd immunity at a global scale; and (4) most infections should cause symptomatic illness. Variola virus was able to meet all the four conditions, but unmet factors (3) and (4) for poliovirus and unmet factor (3) for measles virus make the ongoing effort to eradicate them challenging (Figure 2; Kew et al, 2005;Moss and Strebel, 2011;Furuse and Oshitani, 2017;Chard et al, 2020).…”