More than 500,000 children tested positive for Covid-19 in 3 weeks. Experts say school mask mandates are needed. Pictured is a drive-thru vaccination and testing site in Austin, Texas, on August 5.
Mandatory Credit:	Matthew Busch/BloombergGetty Images

More than 500,000 children tested positive for Covid-19 in 3 weeks. Experts say school mask mandates are needed. Pictured is a drive-thru vaccination and testing site in Austin, Texas, on August 5.
Mandatory Credit: Matthew Busch/BloombergGetty Images

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More than 80% of Americans have some immunity to coronavirus, blood survey finds

More than 80% of Americans have some level of immunity against the coronavirus, mostly through vaccination, a survey of blood donations indicates.