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dcyphr | Consistent detection of 2019 novel coronavirus in saliva.

Note

Summaries from dcyphr do not substitute the advice of health professionals. The information on COVID-19 is constantly changing. Also, this study has an extremely low sample size, and more research needs to be done.


Abstract

Researchers detected the 2019 novel coronavirus in 11 out of 12 (91.7%%) of patients. Saliva taken incrementally showed a decrease in virus concentration with time. Viral culture indicated the presence of live viruses. Saliva testing is promising for detection of 2019-nCoV in patients.


Introduction

The severe acute respiratory syndrome coronavirus (SARS-CoV) caused a global outbreak in 2003. The death rate was 10%%. In December 2019, the 2019 novel coronavirus (2019-nCoV) emerged from the Hubei Province of China. The virus has spread quickly around the world. The 2019-nCoV is similar to bat SARS-like coronaviruses. Based on phylogenetic analyses, the 2019-nCoV is from the Betacoronavirus genus lineage B. The ORF8 and ORF3b proteins of 2019-nCoV is significantly different from other SARS coronaviruses. The difference could be why 2019-nCoV has different mechanisms of infection and transmission. The 2019-nCoV can be transmitted between humans like SARS-CoV.

Currently, hospitals use nasopharyngeal and oropharyngeal swabs to obtain respiratory samples. But, this requires hospital workers to come in close contact with patients. Current testing methods can cause discomfort and bleeding, especially if the patient has a low platelet count. Sputum samples are noninvasive from the lower respiratory tract. But, only 28%% of patients with 2019-nCoV could produce a sample in one study. 

Patients can give saliva samples by spitting in a sterile bottle. This lowers the exposure to healthcare workers. Previously, researchers have shown that saliva samples indicate the same results as nasopharyngeal specimens in coronaviruses. Sometimes, tests can detect respiratory viruses in patients without symptoms. 


Aims

The researchers aim to evaluate if saliva samples are effective for the testing of 2019-nCoV. 


Methods

Patients were confirmed to have 2019-nCoV with a nasopharyngeal or sputum sample. Patients coughed out saliva from their throat into a sterile container. Then, researchers added 2 mL volume of viral transport medium to the sample. Researchers conducted a total nucleic acid extraction. Then, they performed a reverse transcription-quantitative polymerase chain reaction (RT-qPCR) to detect the virus. Viral cultures were used to detect live viruses in saliva specimens.


Results

The study included twelve patients with laboratory-confirmed 2019-nCoV. Researchers collected saliva samples a mean of 2 days after hospitalization. The range was 0-7 days (Figure 1). In 11 out of 12 (91.7%%) of patients, researchers detected 2019-nCoV. Viral load is the amount of virus per volume of fluid. The median viral load of the initial specimens is 3.3 x 106 copies / mL. The range is 9.9 x 102 to 1.2 x 108 copies / mL. 

Samples were incrementally for six patients. The viral load was highest in the first sample for five patients (83.3%%). For one patient, researchers detected viral shedding on day 11 after hospitalization. In 33 patients whose nasopharyngeal tests came back negative, their saliva samples were also negative.


Discussion

Saliva samples provide several advantages. The procedure is noninvasive, and samples can be collected outside of hospitals. Healthcare workers are not required, and results will be available sooner. During the SARS outbreak in 2003, the peak viral load occurred after 10 days of symptom onset on average. Early detection and isolation is important for a decrease in viral load and for antiviral therapies.

The live viral cultures indicate that live viruses are present in saliva. Thus, 2019-nCoV can be transmitted through saliva. This can be in fine respiratory droplets when sneezing or coughing, even without symptoms. Thus, people should wear surgical masks to control the spread. Researchers need to conduct more studies for the source of the virus in saliva. Possible sources include salivary glands, the nasopharynx, or the cilia lining in the lungs.