 Shares of Twist Bioscience Corp. were down 1.6 in premarket trading on Wednesday after the company said its in-vitro diagnostic test that can detect SARS-CoV-2 RNA received emergency authorization in the U.S. Twists test can identify the presence of the virus from a patient sample; it can also be used by Biotia Inc.s software system to analyze the sequence and detect any genetic variants. So-called variants of concern have emerged over the last six months, including the B.1.1.7 variant out of the U.K., which is thought to be more infectious and makes up to 30 of all new U.S. cases, according to the Centers for Disease Control and Prevention. 