SARS-CoV was transmitted after a few days of illness and was associated with only modest viral loads in the respiratory tract early in the illness, with loads peaking 10 days after symptom onset. The authors were interested in the SARS-CoV-2 viral loads in upper respiratory specimens from 18 patients (nine men and nine women; median age 59 years) in Guangdong, Chin. Four of these patients had secondary infections (one of whom never had symptoms) within two family clusters. 72 nasal swabs (mid-turbinate and nasopharynx) and 72 throat swabs were analysed, with 1–9 sequential samples taken from each patient. 13 of the 14 patients with imported cases had evidence of pneumonia on CT. None of them had visited the Huanan Seafood Wholesale Market in Wuhan within 14 days of symptom onset. Three patients required admission to intensive care, while the rest had mild-to-moderate illnesses. Higher viral loads (inversely related to Ct value) were detected soon after symptom onset, particularly in the nose compared with the throat. The viral nucleic acid shedding pattern of patients infected with SARS-CoV-2 resembled that of patients with influenza virus infection, and different to seen with SARS-CoV. The viral load that was detected in the asymptomatic patient was similar to that in the symptomatic patients, suggesting the transmission potential of asymptomatic or minimally symptomatic patients.
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