The US Food and Drug Administration gave emergency authorization Tuesday for a Covid-19 test that can be fully taken at home. Australian company Ellume is sold over-the-counter and produces results that can be read at home. The test uses an analyzer that connects with a software application on a smartphone to help users perform the test and interpret results, the FDA said. Ellume expects to produce more than 3 million tests in January. When it applied for emergency use authorization, the company said it would charge $30 for the test. (Glyco: Can you do the math for us?)