SARS-CoV-2 infectivity
Nasopharyngeal specimens collected on Days 1, 3, 5, 10, 15, and 29 with viral RNA > 100,000 copies/mL were serially diluted in duplicate in serum free Eagle Minimum Essential Media and 100 µL of each dilution placed in a 24-well-plate containing > 90% confluent Vero E6 cells. Samples were incubated with cells for 60 min at 37°C and 5% CO