PBS NewsHour Could enhanced COVID tests help U.S. track virus variants? Right now, even after concerted efforts to increase sequencing capacity, only about 3% of the country’s positive COVID-19 samples were sequenced in early April. That’s not just “unacceptable,” but “nearly worthless,” said Sam Scarpino, a bioinformatics assistant professor at Northeastern University and director of the school’s Emergent Epidemics Lab.