Carol Yepes/Getty Images(WASHINGTON) -- Last month, President Joe Biden announced that 500 million free at-home rapid tests for COVID would be mailed out to American homes. On Thursday, Biden announced that he was doubling that promise and would now ship out another 500 million -- to make 1 billion in total. That's on top of 50 million free at-home tests already sent to community health centers around the country, 20,000 free testing sites and an insurance reimbursement plan that goes into effect on Saturday to allow Americans to get tests covered if they find and buy them at retailers. T...