#VisualAbstract: Viral load dynamics and disease severity in patients infected with SARS-CoV-2 in Zhejiang province, China

1. Stool samples demonstrated significantly longer duration of positive viral load than both respiratory and serum samples.

2. Length of positive RNA detection was associated with disease duration with a peak later in respiratory samples of those with severe disease compared to those with mild disease.

Evidence Rating Level: 2 (Good)

A total of 190 countries have been impacted by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as of March 22, 2020, resulting in over 300,000 confirmed cases and 14,510 deaths. In China specifically, approximately 13.8% of those infected become severely ill and 2.3% eventually pass away. Viral load measurements via tissue samples assist with monitoring progression, response to treatment, remission, and relapse. This retrospective cohort study aimed to estimate viral loads in 3,497 samples obtained from 96 patients following admission with confirmed SARS-CoV-2 and analyze temporal changes in viral loads based on sample types and disease severity. Respiratory (sputum or saliva), stool, serum, and urine samples were collected following admission and whenever possible thereafter to examine the amount of SARS-CoV-2 RNA by polymerase chain reaction (PCR) analysis. RNA was detected in stool samples of 59% of participants and in the serum of 41% of participants; urine from only one participant was positive for the virus. The median duration of SARS-CoV-2 in respiratory samples (18 days) and serum samples (16 days) were significantly shorter than in stool samples (22 days, p = 0.02, p<0.001, respectively). Disease severity was also associated with median duration of the virus in samples. Respiratory samples of participants with severe disease were positive for median duration significantly longer (21 days) than those with mild disease (14 days, p = 0.04). Within this mild group, though, viral loads seemed to peak in respiratory samples in the second week while they remained stable and high during the third week in the severe disease group. Risk factors for increased length of viral load detection included age (>60 years) and gender (male).

Click to read the study in BMJ

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