Detection of SARS-CoV-2 in Different Types of Clinical Specimens

Wang W, Xu Y, Gao R, et al. Detection of SARS-CoV-2 in Different Types of Clinical Specimens. JAMA. Published online March 11, 2020. doi:10.1001/jama.2020.3786

Review written by:

Yucong Wang, Lillian Zerihun

Yellow - Guides testing strategies, but small sample, confounding by illness trajectory or severity

Covering the period from January 1 through February 17, 2020, clinical specimens from different sites were collected from 205 patients in 3 hospitals in China. RNA was extracted from clinical specimens and analyzed by rRT-PCR. Among all kinds of specimens, bronchoalveolar lavage fluid specimens showed the highest positive rates of 93%, followed by sputum of 72%, nasal swabs of 63%, fibrobronchoscope brush biopsy of 46%, pharyngeal swabs of 32%, feces of 29% and blood of 1%. No urine specimens tested positive.

Among all the patients, 7 shed virus in respiratory tract specimens and in feces (n=5) or blood (n=2). Live SARS-CoV-2 was observed in stool samples from 2 patients, which suggests that the virus can be potentially transmitted in other ways including the fecal route. The study also found that a small percentage of blood samples tested positive, suggesting that the infection can become systemic.

Review Notes
 

Limitations include the small sample size and the type of patient being studied (sick hospitalized patients), as well as the small percentage of stool and blood positivity. The small sample size composed of only hospitalized patients makes it difficult to extrapolate results to the general patient population. In addition, the very small percentage of positive stool samples is not strong enough evidence to guide our understanding of whether COVID-19 has fecal transmission. Furthermore, these data do not account for the time in a patient’s illness course or the severity of their symptoms when reporting percent positivity of their collected specimens.

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