Readers ponder differences in polio vaccines and more
Your comments and questions on the September 14, 2019 issue of Science News
Vaccine varieties
Polio is close to being eradicated worldwide, but the virus still circulates in Afghanistan and Pakistan, Tina Hesman Saey reported (SN: 9/14/19, p. 4) in an update to a 1969 story, “Polio could come back” (SN: 9/13/69, p.