The Long-Term Loss of Smell and Taste in COVID-19 Patients – A Systematic Review and Meta-Analysis

Main Article Content

Jaqueline Dal Curtivo Passos
Yan Santos Borges
Henrique Aparecido Laureano
Izonete Cristina Guiloski


Introduction: Olfactory symptoms have been reported as particular in COVID-19 patients. Objective: To synthesize and analyze the existing evidence on the monitoring loss of sense of smell and taste in COVID-19 patients, and for how long symptoms persist after the virus is no longer active in the organism. Methods: A search was implemented in PubMed, Embase, Scopus, Science Direct, and Web of Science databases. This systematic review and meta-analysis were conducted according to PRISMA, and the risk of bias was assessed through the Newcastle-Ottawa Scale. The review protocol is registered in PROSPERO. Results: Our systematic review included data from 14 articles with a total of 2143 participants. The most reported sensory symptom of COVID-19 was anosmia, which was detected in 1499 patients, being the only symptom to appear in all studies. Ageusia was detected in 595 patients, dysgeusia in 514 patients, and hyposmia in 209 patients. The studies provided the number of 729 patients with sensory symptoms during the acute COVID-19 infection of 15 days, and 1020 patients with lasting sensory symptoms, presenting sensory dysfunctions after the average latent period of 15 days of the acute COVID-19 infection. Conclusion: Evidence points to the loss or dysfunction of taste and smell as one of the symptoms of COVID-19 persisting for an average time of 15 days, with 44% of COVID-19 patients with persistent symptoms for more than 15 days. Nevertheless, most studies do not perform a follow-up with those patients. Therefore, further research on sensory symptoms and their follow-up is required.


Download data is not yet available.

Article Details

How to Cite
Passos, J. D. C., Borges, Y. S., Laureano, H. A., & Guiloski, I. C. (2024). The Long-Term Loss of Smell and Taste in COVID-19 Patients – A Systematic Review and Meta-Analysis. ABCS Health Sciences, 49, e024302.
Review Articles
Author Biography

Yan Santos Borges, Faculdades Pequeno Príncipe (FPP) – Curitiba (PR), Brazil /Instituto de Pesquisa Pelé Pequeno Príncipe (IPPPP) – Curitiba (PR), Brazil

1Faculdades Pequeno Príncipe, Programa de Pós-Graduação em Biotecnologia Aplicada à Saúde da Criança e do Adolescente, Curitiba, Paraná, Brazil;

2Instituto de Pesquisa Pelé Pequeno Príncipe, Curitiba, Paraná, Brazil


Naeini AS, Karimi-Galougahi M, Raad N, Ghorbani J, Taraghi A, Haseli S, et al. Paranasal sinuses computed tomography findings in anosmia of COVID-19. Am J Otolaryngol. 2020;41(6):102636.

World Health Organization (WHO). Coronavirus disease (COVID-19) pandemic. Available from:

Kaye R, Chang CWD, Kazahaya K, Brereton J, Denneny JC. COVID-19 Anosmia reporting tool: initial findings. Otolaryngol Head Neck Surg. 2020;163(1):132-4.

Spinato G, Fabbris C, Polesel J, Cazzador D, Borsetto D, Hopkins C, et al. Alterations in Smell or Taste in Mildly Symptomatic Outpatients With SARS-CoV-2 Infection. JAMA. 2020;323(20):2089-90.

Tong JY, Wong A, Zhu D, Fastenberg JH, Tham T. The Prevalence of olfactory and gustatory dysfunction in COVID-19 patients: a systematic review and meta-analysis. Otolaryngol Head Neck Surg. 2020;163(1):3-11.

Wiersinga HCPWJ, Rhodes A, Cheng AC, Peacock SJ. Pathophysiology, transmission, diagnosis, and treatment of Coronavirus disease 2019 (COVID-19) a review. JAMA. 2020;324:782-93.

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

Hannum ME, Ramirez VA, Lipson SJ, Herriman RD, Toskala AK, Lin C, et al. Objective sensory testing methods reveal a higher prevalence of olfactory loss in COVID-19-positive patients compared to subjective methods: a systematic review and meta-analysis. Chem Senses. 2020;45(9):865-74.

Borsetto D, Hopkins C, Philips V, Obholzer R, Tirelli G, Polesel J, et al. Self-reported alteration of sense e of smell or taste in patients with COVID-19: a systematic review and meta-analysis on 3563 patients. Rhinology. 2020;58(5):430-6.

Agyeman AA, Chin KL, Landersdorfer CB, Liew D, Ofori-Asenso R. Smell and Taste Dysfunction in Patients With COVID-19: A Systematic Review and Meta-Analysis. Mayo Clin Proc. 2020;95(8):1621-31.

Moher D, Liberati A, Tetzlaff J, Altman DG; PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: The PRISMA statement. PLoS Med. 2009;6(7):e1000097.

Ottawa Hospital Research Institute (OHRI). Newcastle - Ottawa Quality Assessment Scale. Available from:

Viechtbauer W. Conducting meta-analyses in R with the metafor package. J Statist Software. 2010;36(3):1-48.

R Core Team. A language and environment for statistical computing. R Foundation for Statistical Computing. Vienna: 2018. Available from:

Wickham H, François R, Henry L, Müller K, Vaughan D. dplyr: a Grammar of Data Manipulation. Available from:

Wickham H, Vaughan D, Girlich M, Ushey K. Tyr: Tidy Messy Data. Available from:

Wickham H; RStudio. stringr: Simple, Consistent Wrappers for Common String Operations. Available from:

Wickham H. ggplot2: Elegant Graphics for Data Analysis. New York: Springer-Verlag, 2016.

Viechtbauer W. Conducting meta-analyses in R with the metafor package. Available from:

D’Ascanio L, Pandolfini M, Cingolani C, Latini G, Gradoni P, Capalbo M, et al. Olfactory dysfunction in COVID-19 patients: prevalence and prognosis for recovering the sense of smell. Otolaryngol Head Neck Surg. 2021;164(1):82-6.

Denis F, Septans AL, Periers L, Maillard JM, Legoff F, Gurden H, et al. Olfactory Training and Visual Stimulation Assisted by a Web Application for Patients with Persistent Olfactory Dysfunction After SARS-CoV-2 Infection: Observational Study. J Med Internet Res. 2021;23(5):e29583.

Vaira LA, Deiana G, Fois AG, Pirina P, Madeddu G, De Vito A, et al. Objective evaluation of anosmia and ageusia in COVID-19 patients: Single-center experience on 72 cases. Head Neck. 2020;42(6):1252-8.

Weinbergerova B, Mayer J, Hrabovsky S, Novakova Z, Pospisil Z, Martykanova L, et al. COVID-19’s natural course among ambulatory monitored outpatients. Sci Rep. 2021;11:10124.

Wilton A, Kilich E, Chaudhry Z, Bell LC, Gahir J, Cadman J, et al. Delayed healthcare seeking and prolonged illness in healthcare workers during the COVID-19 pandemic: a single-center observational study. BMJ Open. 2020;10:e040216.

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 Forum Allergy Rhinol. 2020;10(7):806-13.

Gelardi M, Trecca E, Cassano M, Ciprandi G. Smell and taste dysfunction during the covid-19 outbreak: a preliminary report. Acta Biomed. 2020;91(2):230-1.

Joffily L, Ungierowicz A, David AG, Melo B, Brito CLT, Mello L, et al. The close relationship between sudden loss of smell and COVID-19. Braz J Otorhinolaryngol. 2020;86(5):632-38.

Kosugi EM, Lavinsky J, Romano FR, Fornazieri MA, Luz-Matsumoto GR, Lessa MM, et al. Incomplete and late recovery of sudden olfactory dysfunction in COVID-19. Braz J Otorhinolaryngol. 2020;86(4):490-6.

Lechien JR, Chiesa-Estomba CM, De Siati DR, Horoi M, Le Bon SD, Rodriguez A, et al. Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): a multicenter European study. Eur Arch Otorhinolaryngol. 2020;277(8):2251-61.

Leedman SR, Sheeraz M, Sanfilippo PG, Edgar DW, D’Aulerio GV, Robb DM, et al. Olfactory dysfunction at six months after coronavirus disease 2019 infection. J Laryngol Otol. 2021;135(9):839-43.

Paolo G. Does COVID-19 cause permanent damage to olfactory and gustatory function? Med Hypotheses. 2020;143:110086.

Parente-Arias P, Barreira-Fernandez P, Quintana-Sanjuas A, Patiño-Castiñeira B. Recovery rate and factors associated with smell and taste disruption in patients with coronavirus disease 2019. Am J Otolaryngol. 2021;42(5):102648.

Schönegger CM, Gietl S, Heinzle B, Freudenschuss K, Walder G. Smell and taste disorders in COVID-19 patients: objective testing and magnetic resonance imaging in five cases. SN Compr Clin Med. 2020;2(12):2535-9.

Mullol J, Alobid I, Mariño-Sánchez F, Izquierdo-Domínguez A, Marin C, Klimek L, et al. The loss of smell and taste in the COVID-19 outbreak: a tale of many countries. Curr Allergy Asthma Rep. 2020;20(10):61.

Yachou Y, El Idrissi A, Belapasov V, Benali SA. Neuroinvasion, neurotropic, and neuroinflammatory events of SARS-CoV-2: understanding the neurological manifestations in COVID-19 patients. Neurol Sci. 2020;41(10):2657-69.

Sayin I, Yazici ZM. Taste and smell impairment in SARS-CoV-2 recovers early and spontaneously: experimental data strongly linked to clinical data. ACS Chem Neurosci. 2020;11(14):2031-3.

Coelho DH, Reiter ER., Budd SG, Shin Y, Kons ZA, Costanzo RM. Quality of life and safety impact of COVID-19 associated smell and taste disturbances. Am J Otolaryngol. 2021;42(4):103001.

Elkholi S, Abdelwahab MK, Abdelhafeez M. Impact of the smell loss on the quality of life and adopted coping strategies in COVID-19 patients. Eur Arch Otorhinolaryngol. 2021;278(9):3307-14.

Yom-Tov E, Lekkas D, Jacobson NC. Association of COVID-19-induced anosmia and ageusia with depression and suicidal ideation. J Affect Disord Rep. 2021;5:100156.

Mazza MG, De Lorenzo R, Conte C, Poletti S, Vai B, Bollettini I, et al. Anxiety and depression in COVID-19 survivors: Role of inflammatory and clinical predictors. Brain Behav Immun. 2020;89:594-600.