Differences of Severe Acute Respiratory Syndrome Coronavirus 2 Shedding Duration in Sputum and Nasopharyngeal Swab Specimens Among Adult Inpatients With Coronavirus Disease 2019

Abstract

BACKGROUND: The viral shedding duration of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has not been fully defined. Consecutive detection of SARS-CoV-2 RNA from respiratory tract specimens is essential for determining duration of virus shedding and providing evidence to optimize the clinical management of coronavirus disease 2019 (COVID-19). RESEARCH QUESTION: What are the shedding durations of SARS-CoV-2 RNA in the upper and lower respiratory tract specimens? What are their associated risk factors? STUDY DESIGN AND METHODS: A total of 68 patients with COVID-19 admitted to Wuhan Taikang Tongji Hospital and Huoshenshan Hospital from February 10, 2020, to March 20, 2020, were recruited. Consecutive SARS-CoV-2 RNA detection from paired specimens of nasopharyngeal swab (NPS) and sputum were carried out. The clinical characteristics of patients were recorded for further analysis. RESULTS: SARS-CoV-2 RNA was detected from NPSs in 48 patients (70.6%), and from sputum specimens in 30 patients (44.1%). The median duration of viral shedding from sputum specimens (34 days; interquartile range [IQR], 24-40) was significantly longer than from NPSs (19 days; IQR, 14-25; P < .001). Elderly age was an independent factor associated with prolonged virus shedding time of SARS-CoV-2 (hazard ratio, 1.71; 95% CI, 1.01-2.93). It was noteworthy that in 9 patients, the viral RNA was detected in sputum after NPS turned negative. Chronic lung disease and steroids were associated with virus detection in sputum, and diabetes mellitus was associated with virus detection in both NPS and sputum. INTERPRETATION: These findings may impact a test based clearance discharge criteria given patients with COVID-19 may shed virus longer in their lower respiratory tracts, with potential implication for prolonged transmission risk. In addition, more attention should be given to elderly patients who might have prolonged viral shedding duration.

SARS CoV-2 Detection From Upper and Lower Respiratory Tract Specimens

“…Duration of viral genetic shedding was shorter from nasopharyngeal swabs than sputum samples, at 19 and 34 days ( P < .001), respectively. 8 More prolonged RT-PCR detection of viral RNA in lower respiratory specimens has also been shown in other studies when compared with upper respiratory samples. 2 , 6 Wang et al suggest that this more-prolonged shedding in lower respiratory specimens compared with nasopharyngeal specimens may impact infection control policies if a “test based” clearance strategy is used for removing patients from COVID-19 isolation precautions.…”

“…2 , 5 Studies have shown increased sensitivity of lower respiratory tract specimens compared with upper respiratory tract specimens 2 , 6 , 7 ; however, it can be technically challenging and create additional safety and exposure concerns to obtain sputum or BAL samples, particularly in patients who are not intubated. In this issue of CHEST , Wang et al 8 also found that of 68 patients with confirmed COVID-19 infection, 20.6% had negative initial and follow-up nasopharyngeal swabs, but a positive sputum specimen, when tested for SARS CoV-2 by RT-PCR molecular assay. SARS CoV-2 detection by RT-PCR from respiratory specimens remains the primary diagnostic strategy for COVID-19 infection.…”

SARS-CoV and SARS-CoV-2 are transmitted through the air between ferrets over more than one meter distance

“…In the current study, SARS-CoV and SARS-CoV-2 RNA was detected in nose and throat swabs of all infected ferrets. In COVID-19 patients, SARS-CoV-2 RNA was also easily detected in upper respiratory tract (URT) specimens, however the detection rate of SARS-CoV RNA in URT specimens of SARS patients was low, with SARS-CoV RNA detection by RT-PCR in only 32% to 68% of the tested patients 13,17,31,32 . This lower detection rate, likely as a result of lower or no replication of SARS-CoV in the upper respiratory tract, may explain why SARS-CoV was less efficiently transmitted between humans than SARS-CoV-2.…”

Prolonged Positive COVID-19 Test in Recovered Patient

“…Findings of a recent study suggest the transmissivity of the novel coronavirus is significantly decreased among patients who retest positive after recovery from COVID-19 [3]. Several studies on IgG and IgM antibody responses in COVID-19 patients and SARS-CoV-2 viral shedding have been performed [4][5][6][7][8], but further information is crucial to better understand the epidemiological characteristics of this virus. In the present report, we describe a patient with mild clinical manifestations of COVID-19 who tested positive for SARS-CoV-2 for 53 days based on RT-PCR on nasopharyngeal swab, as well as her husband who also tested positive for the virus but had a shorter positive period despite a more moderate presentation of symptoms.…”