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Walmart is experimenting with using drones to deliver at-home COVID-19 tests in a bid to provide more contactless testing options, the superstore chain announced Tuesday. Walmart has partnered with lab company Quest Diagnostics and DroneUp, a drone services provider, to perform trial deliveries of test collection kits in Las Vegas and Cheektowaga, N.Y. The trials will begin immediately in Las Vegas and take place in Cheektowaga early next month. (Livingston, 9/22)

More than 100,000 people are taking part in studies to see if one or more COVID-19 vaccine candidates actually work. Janssen Pharmaceutical Cos. of Johnson & Johnson is about to start wide-scale testing for its vaccine. It will involve as many as 30,000 volunteers. AstraZeneca, Pfizer and Moderna already have vaccine candidates in large studies in the United States. Novavax should start its study later this fall. The reason the trials are so large has to do with the complications of getting an accurate analysis of whether the vaccine works — and how the scientists and public health officials define "works." (Palca, 9/23)

More than 100 million COVID-19 tests have been performed in the United States, according to the Centers for Disease Control and Prevention's COVID Data Tracker. But the true number of tests is unknown because of decentralized accounting and the fact that not all tests were created equally. (Croll and Salzman, 9/23)