How effective was Jonas Salk’s initial testing of the polio vaccine?

it was very effective.

Explanation:

According to report in America 1954, Salk conducted a national study, with over a million paediatric subjects wish yielded a positive outcome and on 12 April 1955, the vaccine was considered safe and efficacious. in 1955, the vaccines was used for over 29,000 cases of poliomyelitis in the US and the infection rate reduced to less than 6,000. This made Salk vaccine more recognized and it was speedily adopted worldwide reaching almost 90 countries in less than 2 years after it mass production.

by drinking easy

very easy