This is interesting: CDC Reports Sharp Increase in Vaccine-Derived Poliovirus Outbreaks

[mfcorey1]

From December 2019


The number of circulating vaccine-derived poliovirus (cVDPV) outbreaks worldwide more than tripled to 29 in 15 countries between January 2018 and June 2019, according to an update from the US Centers for Disease Control and Prevention. That compares with 9 outbreaks in 6 countries during the previous reporting period (January 2017–June 2018).

“Worldwide over the past 10 years, over 12 billion doses of OPV [oral poliovirus vaccine] have been administered to more than 2.5 billion children, and as a result more than 3.5 million polio cases were prevented,” first author Jaume Jorba, PhD, told Contagion®. “During that time, 1085 cases of paralysis caused by cVDPV have been reported.”

The report found that 86% of cVDPV cases were caused by cVDPV type 2, occurring both inside and outside of areas where monovalent type 2 OPV was used to control the cVDPV2 vaccine strain. In 2016, world health officials switched from trivalent oral poliovirus vaccine (tOPV, types 1, 2 and 3) to bivalent oral poliovirus vaccine (bOPV types 1 and 3).

https://www.contagionlive.com/news/cdc-reports-sharp-increase-in-vaccinederived-poliovirus-outbreaks

[Voltaire2]

1. 1085 cases out of 2.5 billion over 10 years.

And the 2.5 billion children vaccinated prevented an estimated 3.5 million new cases.

Do the math.

Also work is in progress on a better vaccine.