Loss of Smell and Taste as Clinical Onset of COVID-19

*Nihal Seden*

## **Abstract**

Initially, symptoms of COVID-19 associated with Ear-Nose-Throat were thought to be flulike symptoms in the foreground. Such as fever, chills, cough, dyspnoea, myalgia, headache, sore throat. Olfactory and gustatory dysfunction was not a noticeable symptom at first. As the number of cases has risen worldwide, sudden onset hyposmia/anosmia has received increasing attention as a symptom of COVID-19. The reported incidence of anosmia varies internationally: as low as 30% in South Korea, and as high as 88% in Europe. The loss of smell that occurs in COVID-19 infection its general character is sudden onset anosmia. There is currently no specific treatment for COVID-19 related anosmia. Olfactory dysfunction can heal spontaneously. However, not a small number of patients may have permanent impairment.

**Keywords:** olfactory dysfunction, postviral anosmia, COVID-19 related anosmia, ENT

## **1. Introduction**

Like all healthcare workers, Ear-Nose-Throat (ENT) specialists did not hesitate to take part in the forefront of the epidemic, and investigated the issues where they could benefit both in terms of their expertise and as primary physicians in combating the pandemic.

Initially, symptoms of COVID-19 associated with ENT were thought to be flulike symptoms in the foreground. Such as fever, chills, cough, dyspnoea, myalgia, headache, sore throat, etc. [1]. Olfactory and gustatory dysfunction was not a noticeable symptom at first. In the first studies reported from China, there were no evidence of patients with symptoms of changes and/or loss of smell and taste [2–4]. As the number of cases has risen worldwide, sudden onset hyposmia/anosmia was received increasing attention as a symptom of COVID-19. Due to the efforts of the American Academy of Otolaryngology-Head and Neck Surgery and the British Association of Otorhinolaryngology-Head and Neck Surgery, sudden onset hyposmia and anosmia were accepted as symptoms of COVID-19 by the Centers for Disease Control and Prevention (CDC) and the World Health Organization on 17 April 2020 and 4 May 2020, respectively [5–7]. The reported incidence of anosmia varies internationally: as low as 30% in South Korea, and as high as 88% in Europe [8]. Various hypotheses are on the agenda as to what might cause this difference. One hypothesis is focused on the ethnicity-host factor. A meta-analysis, reported on nearly 40,000 patients across 104 studies found that anosmia (and ageusia) is more prevalent in Caucasians than Asians (54.8 vs. 17.7%, respectively) [9]. In another hypothesis, spike protein mutations pathogenic factor - are questioned as the cause of the difference in smell loss [10].

In a multicenter European study, a total of 357 patients (85.6%) had olfactory dysfunction related to COVID-19 infection. Among them, 284 (79.6%) patients were anosmic, and 73 (20.4%) were hyposmic. Phantosmia and parosmia were noted in 12.6% and 32.4% of the patients during the disease course, respectively [11]. As we leave behind a year of the pandemic today, the sudden onset of odor loss and taste disturbance are now among the most important ENT-related symptoms, and olfactory disorder is the best predictor of COVID-19 status of all the associated symptoms [12].
