Feasibility of sputum testing for detection of COVID-19

Arvind Sharma, Tej Pratap Singh


For the prevention of COVID-19 spread, early and accurate detection is important. Specimens are collected through respiratory mucosal surfaces with nasopharyngeal or oropharyngeal swabs, from infected patients are highly complex. Sputum testing could preferably be a more convenient technique for the detection of COVID-19 as being noninvasive method, which could easily be collected by having a patient cough deeply to produce and expel phlegm which could be in compliance to patient in comparison to Nasopharyngeal swab (NPS). Consequently, broader testing than the current methods of nasal or throat swabs will significantly increase the number of people screening, leading to more effective control of the spread of COVID-19. Nonetheless, a comparison of the saliva-based assay with current swab test is needed to understand what and how we can benefit from this newly developed assay. Therefore, in this review article, we aimed to summarize the feasibility of sputum testing in relation to Covid-19. Any implementation of clinical sampling for diagnosis should take into considerations of the sensitivity of assays, risks to healthcare professionals, and global shortage of equipment.


COVID-19, SARS-CoV-2, Sputum sample, Sputum testing

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World Health Organization. Coronavirus disease (COVID-19) situation reports, 2020. Available at: Accesed on 15 Dec 2020.

World Health Organization. Coronavirus disease (COVID-19) situation reports, 2020. Available at: Accesed on 15 Dec 2020.

WHO Laboratory testing for 2019 novel coronavirus (2019-nCoV) in suspected human cases. Interim guidance, Jan 17, 2020. Available at:///C:/Users/HP/Downloads/WHO-COVID-19-laboratory-2020.5-eng.pdf. Accesed on 8 January 2021.

Mohammadi A, Esmaeilzadeh E, Li Y, Bosch RJ, Li JZ. SARS-CoV-2 detection in different respiratory sites: A systematic review and meta-analysis. EBioMedicine. 2020;59:102903.

Yoon JG, Yoon J, Song JY, Yoon SY, Lim CS, Seong H, et al. Clinical Significance of a High SARS-CoV-2 Viral Load in the Saliva. J Korean Med Sci. 2020;35(20):195.

Yu F, Yan L, Wang N, Yang S, Wang L, Tang Y, et al. Quantitative Detection and Viral Load Analysis of SARS-CoV-2 in Infected Patients. Clin Infect Dis. 2020;71(15):793-98.

Kim ES, Chin BS, Kang CK, Kim NJ, Kang YM, Choi JP, et al; Korea National Committee for Clinical Management of COVID-19. Clinical Course and Outcomes of Patients with Severe Acute Respiratory Syndrome Coronavirus 2 Infection: a Preliminary Report of the First 28 Patients from the Korean Cohort Study on COVID-19. J Korean Med Sci. 2020;35(13):142.

Wang W, Xu Y, Gao R, Lu R, Han K, Wu G, et al. Detection of SARS-CoV-2 in Different Types of Clinical Specimens. JAMA. 2020;323(18):1843-4.

Wu J, Liu J, Li S, Peng Z, Xiao Z, Wang X, et al. Detection and analysis of nucleic acid in various biological samples of COVID-19 patients. Travel Med Infect Dis. 2020;37:101673.

Pan Y, Zhang D, Yang P, Poon LLM, Wang Q. Viral load of SARS-CoV-2 in clinical samples. Lancet Infect Dis. 2020;20(4):411-2.

Zhang W, Du RH, Li B, Zheng XS, Yang XL, Hu B, et al. Molecular and serological investigation of 2019-nCoV infected patients: implication of multiple shedding routes. Emerg Microbes Infect. 2020;9(1):386-9.

Guo WL, Jiang Q, Ye F, Li SQ, Hong C, Chen LY, et al. Effect of Throat Washings on Detection of 2019 Novel Coronavirus. Clin Infect Dis. 2020;71(8):1980-1.

Han H, Luo Q, Mo F, Long L, Zheng W. SARS-CoV-2 RNA more readily detected in induced sputum than in throat swabs of convalescent COVID-19 patients. Lancet Infect Dis. 2020;20(6):655-656.

Falsey AR, Formica MA, Walsh EE. Yield of sputum for viral detection by reverse transcriptase PCR in adults hospitalized with respiratory illness. J Clin Microbiol. 2012;50(1):21-4.

Jeong JH, Kim KH, Jeong SH, Park JW, Lee SM, Seo YH. Comparison of sputum and nasopharyngeal swabs for detection of respiratory viruses. J Med Virol. 2014;86(12):2122-7.

Branche AR, Walsh EE, Formica MA, Falsey AR. Detection of respiratory viruses in sputum from adults by use of automated multiplex PCR. J Clin Microbiol. 2014;52(10):3590-6.

Lieberman D, Lieberman D, Shimoni A, Keren-Naus A, Steinberg R, Shemer-Avni Y. Identification of respiratory viruses in adults: nasopharyngeal versus oropharyngeal sampling. J Clin Microbiol. 2009;47(11):3439-43.

Li L, Chen QY, Li YY, Wang YF, Yang ZF, Zhong NS. Comparison among nasopharyngeal swab, nasal wash, and oropharyngeal swab for respiratory virus detection in adults with acute pharyngitis. BMC Infect Dis. 2013;13:281.

Mandel ID. The diagnostic uses of saliva. J Oral Pathol Med. 1990;19(3):119-25.

Chen L, Zhao J, Peng J, Li X, Deng X, Geng Z, et al. Detection of SARS-CoV-2 in saliva and characterization of oral symptoms in COVID-19 patients. Cell Prolif. 2020;53(12):12923.

Hung KF, Sun YC, Chen BH, Lo JF, Cheng CM, Chen CY, et al. New COVID-19 saliva-based test: How good is it compared with the current nasopharyngeal or throat swab test? J Chin Med Assoc. 2020;83(10):891-4.

Chen C, Gao G, Xu Y, Pu L, Wang Q, Wang L, et al. SARS-CoV-2-Positive Sputum and Feces After Conversion of Pharyngeal Samples in Patients With COVID-19. Ann Intern Med. 2020;172(12):832-4.

Wölfel R, Corman VM, Guggemos W, Seilmaier M, Zange S, Müller MA, et al. Virological assessment of hospitalized patients with COVID-2019. Nature. 2020;581(7809):465-9.

Thwe PM, Ren P. Analysis of sputum/tracheal aspirate and nasopharyngeal samples for SARS-CoV-2 detection by laboratory-developed test and Panther Fusion system. Diagn Microbiol Infect Dis. 2021;99(1):115228.

Lin C, Xiang J, Yan M, Li H, Huang S, Shen C. Comparison of throat swabs and sputum specimens for viral nucleic acid detection in 52 cases of novel coronavirus (SARS-Cov-2)-infected pneumonia (COVID-19). Clin Chem Lab Med. 2020;58(7):1089-4.