On a Saturday in September 2020, with Covid-19 killing more than 600 Americans daily and hundreds of thousands of deaths still to come, Dr. Deborah L. Birx, a member of the White House coronavirus task force, heard her cellphone ring. It was Dr. Scott Rivkees, the Florida surgeon general. He was distraught.
“‘You won’t believe what happened,’” she said he told her. Months before Covid vaccines would become available, Gov. Ron…