The polio vaccine and public health

On the day in 1955 that Jonas Salk's polio vaccine was pronounced "80 to 90 percent effective" against the form of the disease that caused paralysis, 500 medical scientists and 150 reporters jammed into an auditorium at the University of Michigan for the announcement.

- By SHERYL GAY STOLBERG

Pots clanged, horns honked and factory whistles blew around the country.

In the seven decades since, polio—a disease that once killed or paralyzed more than half a million people around the world each year—has been vanquished in the United States.

A lawyer advising Robert F. Kennedy Jr. has asked the Food and Drug Administration to revoke its approval of the current polio vaccine, a successor to the Salk vaccine, because it has not been tested against a placebo.

Experts say the move would be disastrous because the polio virus is still around.