NHLBI is issuing a Notice of Special Interest (NOSI) to highlight the urgent need for research on Coronavirus Disease 2019 (COVID-19) and on biological effects of its causative agent, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Topics of specific interest to NHLBI include host response, associations with heart, lung, and blood (HLB) diseases, potential impacts on transfusion safety, and clinical outcomes of infected individuals.