Lessons from vaccine-related poliovirus in Israel, UK and USA

Detecting genetic variants of Sabin vaccine virus type 2 in sewage in Israel, London and New York in 2022, is disturbing information. Wild poliovirus type 2 was eradicated in 1999. Sabin virus type 2 was discontinued globally in 2016. Yet, type 2 vaccine virus variants are still circulating in many low income countries from where they were imported into these new locations, showing that the immunisation tactics of polio eradication programme was flawed. Outbreaks of polio caused by type 2 vaccine virus variants occurred in 35 countries during 2018 to 2021, paralysing 2296 children. Immunisation tactics must be corrected urgently. The tactics was designed assuming that the route of wild virus transmission was faecal-oral, for which the orally fed Sabin vaccine was promoted in low income countries, despite its low efficacy and safety. Vaccine variant viruses mimic wild-virus behaviour of contagiousness and neurovirulence. The sustained circulation of imported viruses in London and New York cannot be via faecal-oral route, but via respiratory route. There is no evidence supporting faecal-oral transmission in low income countries; all evidences support respiratory route. Exclusive use of Sabin vaccine has resulted in the conundrum of persistence of type 2 vaccine-derived virus, delayed eradication of wild virus type 3 (13 years after type 2) and failure to eradicate type 1 even now. Salk inactivated poliovirus vaccine (IPV) is completely safe and exquisitely efficacious to prevent polio. Both UK and USA give only IPV during the last two decades. There is no polio case in London and only one in New York in an individual who had refused vaccination. The world should be weaned off the live vaccine under cover of immunity induced by IPV.