Medical workers take a sample at a COVID-19 drive-thru testing site in Washington D.C., the United States, on April 28, 2020. The number of COVID-19 cases in the United States topped 1 million Tuesday afternoon, reaching 1,002,498 as of 1:55 p.m. (1755 GMT), according to the Center for Systems Science and Engineering at Johns Hopkins University. (Photo by Ting Shen/Xinhua)
