The Salk vaccine, generally known as the inactivated polio vaccine (IPV), developed first and used exclusively in the US since 2000, is incredibly effective (99%+) at preventing paralytic poliomyelitis but does not convey mucosal immunity, and therefore does little to reduce transmission of the poliovirus. . . .

The live attenuated Oral Polio Vaccine, developed by Dr. Albert Sabin, is cheap, easy (taken as a few drops of liquid by mouth), and remarkably effective both at preventing infection in the gut as well as severe neurological disease, but has an Achilles heel: it can mutate back into a virulent form of polio!

So when you blame the “unvaccinated” for the spread of polio, you’re wrong. One vaccine doesn’t stop the spread, the other does — except when it causes the spread.

Plus: “We really don’t know how long the immunity from polio vaccination lasts.”

That’s encouraging. I had both kinds of vaccine as a kid, and have always assumed lifetime immunity. Maybe not!