A Study to Evaluate the Safety, Pharmacokinetics (PK), and Efficacy of TAK-671 for the Treatment of Coronavirus Disease (COVID) 2019 in Adults

The drug being tested in this study is called TAK-671. The study will evaluate the safety, tolerability and PK of TAK-671 in participants admitted to the hospital with a confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive test. The study will enroll approximately 40 participants. Each cohort will have 20 participants. Participants will be randomly assigned (by chance, like flipping a coin) in a 3:1 ratio to receive TAK-671 or placebo in each cohort, which will remain undisclosed to the participant during the study (unless there is an urgent medical need): * Cohort 1: TAK-671 Low Dose * Cohort 2: TAK-671 High Dose Enrollment in Cohort 2 will only begin once all 20 participants in Cohort 1 have reached Day 7 post dose and have received positive review from the internal review committee (IRC) and approval to continue enrollment. All participants will receive the standard of care along with the study treatment. This multi-center trial will be conducted in the United States. The overall time to participate in this study is approximately 3 months. All participants will be followed up 28 days after the infusion.