Well, it's complicated. As I understand, one of the polio vaccines - the oral one - has an unusual quirk.
The live virus used in it can reproduce and spread in low-vaccination communities. While the vaccine version of it will not cause paralysis, it can and occasionally does mutate back into a pathogenic variant.
So we're sort of maintaining a reservoir of polio, really.
The live virus used in it can reproduce and spread in low-vaccination communities. While the vaccine version of it will not cause paralysis, it can and occasionally does mutate back into a pathogenic variant.
So we're sort of maintaining a reservoir of polio, really.