Hong Kong researchers who tested 68 respiratory specimens from 35 COVID-19 patients, of whom 32 had mild illness, found that live virus and evidence of viral replication were rarely detectable beyond 8 days after symptom onset but that viral RNA was detectable for many weeks using RT-PCR.The study, published today in Emerging Infectious Diseases, involved isolating viable coronavirus in culture, detecting viral replication on subgenomic RNA (sgRNA), and identifying COVID-19 RNA on RT-PCR.
The researchers isolated live virus from 16 specimens from 16 patients with high median viral loads, while specimens with low viral loads tended to culture negative.Differences in mild, critical infectionsIn addition to virus culture, specimens with a