https://ift.tt/2wwdHAe Virus variants are spreading in the U.S., threatening to prolong the pandemic. internal-essential BY APOORVA MANDAVILLI AND BENJAMIN MUELLER https://ift.tt/3ukbktw April 4, 2021 at 06:38AM

By BY APOORVA MANDAVILLI AND BENJAMIN MUELLER from NYT World https://ift.tt/3dvopJI