Smell and taste abnormalities: early clinical biomarkers for isolating the positive cases in COVID-19 pandemic


  • Santosh Kumar Swain Department of Otorhinolaryngology, IMS and SUM Hospital, Siksha “O” Anusandhan University, Bhubaneswar, Odisha, India



COVID-19 infection, SARS-CoV-2, Smell disturbance, Taste disturbance


Coronavirus disease 2019 (COVID-19) is an infectious disease of the respiratory tract caused by a novel virus called severe acute respiratory syndrome corona virus 2 (SARS-Co-2). It primarily spread human to human by droplets which carry virus. The common clinical presentations of the COVID-19 patients are fever, cough, fatigue, gastrointestinal symptoms and dyspnea. Smell and taste abnormalities have recently documented among patient with COVID-19 infection which hypothesize that olfactory mucosa and oral cavity mucosal lining possess SARS-CoV-2 virus. Some COVID-19 patients are also presenting with isolated smell and taste disturbances even without any other respiratory symptoms. Currently there is no effective treatment available for COVID-19 infections. So screening, early diagnosis and isolations are essential in this pandemic. Identifying the early symptoms in COVID-19 patient is priority now in health care system. In COVID-19 pandemic, patient presenting with loss of smell and taste should initiate home isolation and social distancing for avoiding further spread of this disease. This can be confirmed by diagnostic test such as reverse transcriptase-polymerase chain reaction (RT-PCR) when available. Sudden onset of smell/olfactory and taste/gustatory dysfunctions should be considered in routine work up and screening of the patients with COVID-19 infection. This review article focuses on the smell and taste abnormalities among COVID-19 patient which will surely increase the awareness among the front liner clinicians and help them for early diagnosis of the patient and their management.


Zhu N, Zhang D, Wang W, Li X, Yang B, Song J et al. A novel coronavirus from patients with pneumonia in China, 2019. N Engl J Med. 2020;382:727-33.

Swain SK, Agrawal R. Mastoid surgery: a high-risk aerosol generating surgical procedure in COVID-19 pandemic. Int J Otorhinolaryngol Head Neck Surg. 2020;6:1-6.

Van Riel D, Verdijk R, Kuiken T. The olfactory nerve: a shortcut for influenza and other viral diseases into the central nervous system. J Pathol.2015;235(2):277-87.

Coronavirus disease 2019 (COVID-19) Situation Report-111. 2019. aviruse/situation-reports/20200410-sitrep-81-covid-19.pdf? sfvrsn=ca96eb84_2. Accessed 10 May 2020.

Mao L, Wang M, Chen S. Neurological manifestations of hospitalized patients with COVID-19 in Wuhan, China: a retrospective case series study. MedRXiv. 2020.

Vaira LA, Salzano G, Deiana G, De Riu G. Anosmia and ageusia: common findings in COVID-19 patients. Laryngoscope. 2020;130(7):1787.

Gane SB, Kelly C, Hopkins C. Isolated sudden onset anosmia in COVID-19 infection. A novel syndrome? Rhinol. 2020;58(3):299-301.

Moein ST, Hashemian SMR, Mansourafshar B, Khorram-Tousi A, Tabarsi P, Doty RL. Smell dysfunction: a biomarker for COVID-19. Int Forum Allergy Rhinol. 2020;10(8):944-50.

Liu G, Zong G, Doty RL, Sun Q. Prevalence and risk factors of taste and smell impairment in a nationwide representative sample of the US population: a cross-sectional study. BMJ Open. 2016;6(11):e013246.

De Wilde AH, Snijder EJ, Kikkert M, Van Hemert MJ. Host factors in corona virus replication. Curr Top Microbiol Immunol. 2018;419:1-42.

Richman DD, Whitley RJ, Hayden FG. Clinical Virology, 4th ed. Washington: ASM Press; 2016.

Bai Y, Yao L, Wei T, Tian F, Jin DY, Chen L, et al. Presumed asymptomatic carrier transmission of COVID-19. Jama. 2020;323(14):1406-7.

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. Emerging microbes and infections. 2020;9(1):386-9.

Gane SB, Kelly C, Hopkins C. Isolated sudden onset anosmia in COVID-19 infection. A novel syndrome? Rhinol. 2020;2:10.

Trotier D, Bensimon JL, Herman P, Tran Ba Huy P, Døving KB, Eloit C. Inflammatory obstruction of the olfactor y clefts and olfactory loss in humans: a new syndrome? Chem Senses. 2006;32(3):285-92.

Mullol J, Mariño-Sánchez F, Valls M, Alobid I, Marin C. The sense of smell in chronic rhinosinusitis. J Allergy Clin Immunol. 2020;145:773-6.

Van Riel D, Verdijk R, Kuiken T. The olfactory nerve: a shortcut for influenza and other viral diseases into the central nervous system. J Pathol. 2015;235(2):277-87.

Swain SK, Behera IC. Managing pediatric otorhinolaryngology patients in coronavirus disease-19 pandemic-A real challenge to the clinicians. Indian J Child Health. 2020;7(9):357-62.

Bilinska K, Jakubowska P, Von Bartheld CS, Butowt R. Expression of the SARS-CoV-2 entry proteins, ACE2 and TMPRSS2, in cells of the olfactory epithelium: identification of cell types and trends with age. ACS Chem Neurosci. 2020;11(11):155-62.

Li YC, Bai WZ, Hashikawa T. Response to Commentary on, The neuroinvasive potential of SARS‐CoV‐2 may play a role in the respiratory failure of COVID‐19 patients. J Med Virol. 2020;92:707-9.

Yan CH, Faraji F, Prajapati DP, Boone CE, DeConde AS. Association of chemosensory dysfunction and Covid‐19 in patients presenting with influenza‐like symptoms. Int allergy rhinol. 2020;10(7):806-13.

Netland J, Meyerholz DK, Moore S, Cassell M, Perlman S. Severe acute respiratory syndrome coronavirus infection causes neuronal death in the absence of encephalitis in mice transgenic for human ACE2. J Virol. 2008; 82(15):7264-75.

Baig AM, Khaleeq A, Ali U, Syeda H. Evidence of the COVID-19 virus targeting the CNS: tissue distribution, host–virus interaction, and proposed neurotropic mechanisms. ACS Chem Neurosci.2020; 11(7):995–98.

Akerlund A, Bende M, Murphy C. Olfactory threshold and nasal mucosal changes in experimentally induced common cold. Acta Otolaryngol. 1995;115:88-92.

Guan WJ, Ni ZY, Hu Y, Liang WH, Ou CQ, He JX et al. Clinical characteristics of coronavirus disease 2019 in China. N Eng j med. 2020;382(18):1708-20.

Chen N, Zhou M, Dong X, Qu J, Gong F, Han Y, et al. Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. Lancet. 2020;395(10223):507-13.

Swain SK, Das S, Padhy RN. Performing tracheostomy in intensive care unit-A challenge during COVID-19 pandemic. Siriraj Med J. 2020;72(5):436-42.

Hong CZ-s, Yang TY, Deng CS, Jun JH, Sen JH, Yun WD, et al. The origin, transmission and clinical therapies on coronavirus disease 2019 (COVID-19) outbreak-an update on the status. Mil Med Res. 2020;7:11.

Sayin I, Yasar KK, Yazici ZM. Taste and Smell Impairment in COVID-19: An AAOHNS Anosmia Reporting Tool-Based Comparative Study. Otolaryngol Head Neck Surg. 2020;163(3):473-9.

Walker A, Hopkins C, Surda P. The use of google trends to investigate the loss of smell related searches during COVID-19 outbreak. Int Forum Allergy Rhinol. 2020;10(7):839-47.

Menni C, Valdes AM, Freidin MB, Sudre CH, Nguyen LH, Drew DA et al. Real-time tracking of self-reported symptoms to predict potential COVID-19. Nature med. 2020;11:1-4.

Bagheri SHR, Asghari AM, Farhadi M, Shamshiri AR, Kabir A, Kamrava SK et al. Coincidence of COVID-19 epidemic and olfactory dysfunction outbreak. medRxiv. 2020;20041889.

Wehling E, Nordin S, Espeseth T. Unawareness of olfactory dysfunction and its association with cognitive functioning in middle aged and old adults. Arch Clin Neuropsychol. 2011;26(3):260-9.

Mariño-Sánchez F, Santamaría A, De los Santos G, Alobid I, Mullol J. Psychophysical olfactory testing in COVID-19: is smell function really impaired in nearly all patients? Int Forum Allergy Rhinol. 2020; 10(8):951-2.

Swain SK, Acharya S, Sahajan N. Otorhinlaryngological manifestations in COVID-19 infections: An early indicator for isolating the positive cases. J Sci Soc. 2020;47:63-8.

Wang C, Horby PW, Hayden FG, Gao GF. A novel coronavirus outbreak of global health concern. Lancet. 2020;395(10223):470-3.

Hummel T, Whitcroft KL, Andrews P, Altundag A, Cinghi C, Costanzo RM et al. Position paper on olfactory dysfunction. Rhinol Suppl. 2017;54:1-30.

Bousquet J, Akdis C, Jutel M, Bachert C, Klimek L, Agache I, et al. Intranasal corticosteroids in allergic rhinitis in COVID‐19 infected patients: An ARIA‐EAACI statement. Allergy. 2020.

Swain SK, Behera IC, Das A, Mohanty JN. Normal saline nasal irrigation in childhood allergic rhinosinusitis: Our experiences in a tertiary care teaching hospital of Eastern India. Indian J Child Health. 2019:265-8.






Review Articles