![](https://scx1.b-cdn.net/csz/news/tmb/2019/1-morepoliocas.jpg)
More polio cases now caused by vaccine than by wild virus
Four African countries have reported new cases of polio linked to the oral vaccine, as global health numbers show there are now more children being paralyzed by viruses originating in vaccines than in the wild.
Nov 25, 2019
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