- Anosmia/hyposmia and ageusia are present in a majority of Covid-19 patients (5, 6)
- These symptoms are significantly more frequent in COVID-19 patients than influenza patients(1) and influenza-like patients. (6)
- They usually have an acute onset and commonly present as an initial manifestation. (1,5)
- Most patients reported complete or partial recovery of smell and taste. (1,6)
- Global authorities, mainly UK and France, do not recommend the use of oral steroids in the treatment of new onset anosmia during the pandemic, as it may increase the severity of infection. (2,3,4)
- Loss of smell in the absence of other symptoms could be used as an additional criteria to trigger quarantine and for healthcare personnel to take extra precautions. (2,3,4)
These statements come from documents produced by SFORL, ENT UK and INESSS in regards to the growing evidence of anecdotal cases of patients developing anosmia/hyposmia with proven COVID-19 in South Korea, China, Italy and Germany. In addition, there has been a significant increase in patients presenting with anosmia, often associated with ageusia, without other symptoms in the UK, US, France, Northern Italy and Iran. This presentation is generally observed in young patients with benign form of COVID-19.
Lechien et al’s study investigated 417 mild-to-moderate COVID-19 patients in different European hospitals. 85,6% and 88,0% of patients reported olfactory and gustatory dysfunction, respectively. in 11,8% of cases, olfactory dysfunction appeared before the other symptoms.
Bertran-Corbellini et al’s study compared 79 COVID-19 cases with 40 influenza patients (historical control sample). They were assessed by a self-reported smell and/or taste disorder (STD) questionnaire. STD was more frequent in cases (39,2%) than in control group (12.5%). Among cases, 70,9 % reported an acute onset, and 35,5% recalled these symptoms are an initial manifestation. 40% of cases reported full recovery after 7.4 +/- 2.3 days and 16,7 % partial recovery after 9.1+/-3.6 days.
Yan et al’ study investigated 59 COVID-19 positive patients and 203 COVID-19 negative patients with a online survey. These patients underwent PCR testing between March 3, 2020 and March 29, 2020 following influenza-like symptoms. Anosmia and ageusia were reported in 68% and 71% of COVID-19 positive cases, compared to, 16% and 17% , respectively, in negative patients. In 74% of positive patients, anosmia was resolved with clinical resolution of illness.
- Beltran-Corbellini A., Chico-Garcia JL., Martinez-Poles J., et al (April 22, 2020) Acute-onset Smell and Taste Disorders in the Context of COVID-19: A Pilot Multicenter PCR-based Case-Control Study, European Journal of Neurology. https://doi.org/10.1111/ene.14273
- Béquignon E., Corré A., Hautefort C., et al (20 March 2020). Alerte anosmie COVID-19. Société française d’ORL et de chirurgie de la face et du cou. Retrieved from https://www.sforl.org/actualites-covid-19/
- Hopkins, C., Kumar N. (21 March 2020). Loss of sense of smell as marker of COVID-19 infection. ENT UK. Retrieved from https://www.entuk.org/anosmia-potential-marker-covid-19-infection-%E2%80%93-update
- INESSS. (24 March 2020). COVID-19 et anosmie sévère BRUTALE et perte de goût sans obstruction nasale. Retrieved from https://www.inesss.qc.ca/covid-19/presentations-cliniques.html
- Lechien JR., Chiesa-Estomba CM., De Siati DR., et al (April 6, 2020) Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): a multicenter European study, European Archives of Oto-Rhino-Laryngology. https://doi.org/10.1007/s00405-020-05965-1
- Yan CH., Faraji F., Prajapati BS DP., et al (April 12, 2020) Association of chemosensory dysfunction and COVID-19 in patients presenting with influenza-like symptoms, International Forum of Allergy & Rhinology. https://doi.org/10.1002/alr.22579