Is taste and smell impairment irreversible in COVID-19 patients?

Abstract

Objective It is known that the COVID-19 disease, which has affected the whole world, causes symptoms, such as cough, fever, shortness of breath, muscle pain, fatigue, diarrhea, headache and sore throat, in addition to various clinical findings, such as loss of smell and taste. In this study, we aimed to reveal the loss of sense of taste and smell in COVID-19 patients and to investigate whether these sensory losses are permanent in the healing process of the disease. Method This prospective study included 94 COVID-19 patients. Smell and taste tests were applied to all patients. Ten days after the first test, a second test was applied to the patients with an impaired sense of smell to compare the results. Results Of the 94 patients, 55.3% were male, and the mean age was 53 ± 19.6 (21-90) years. There were 67 patients with smell and taste impairment, of whom 34 (50.7%) had smell impairment only, 3 (4.4%) had taste impairment only, and 30 (44.7%) had both smell and taste impairment. It was found that the smell scores of 55 patients with smell and taste impairment in the first evaluation were significantly higher at the second measurement; and their tasting period was significantly shortened compared to the first measurement (p˂0.001). Conclusion COVID-19 patients may present to medical centers with a broad variety signs and symptoms. This study shows that impairment in the senses of smell and taste is common in this disease and strongly associated with COVID-19 infection. However, smell and taste impairment is mostly temporary and improves during the recovery period.

Olfactory recovery following infection with COVID-19: A systematic review

“…The remaining 18 studies were conducted in other regions (a pie chart showing distribution is included in the supplementary data provided— S1 Fig ). 10 studies were conducted in Asia: Turkey (n = 5) [ 18 , 27 , 38 , 41 , 50 ], Iran (n = 2) [ 22 , 55 ], India (n = 2) [ 33 , 52 ], Israel (n = 1) [ 32 ]. Four studies were conducted in North America: United States (n = 4), [ 21 , 42 , 48 , 51 ].…”

“…Two studies were conducted in Africa: Egypt (n = 2) [ 34 , 49 ], and two in South America: Brazil (n = 1) [ 53 ], Chile (n = 1) [ 15 , 53 ]. Of the 44 studies, twenty-five (56.8%) reported no funding requirements for the project [ 16 , 18 , 19 , 22 , 27 – 30 , 32 , 33 , 39 , 40 , 42 – 47 , 49 – 51 , 53 , 58 ]; six (13.6%) studies reported funding for the project (sources included academic institutions, government and not-for-profit organizations) [ 15 , 24 , 25 , 31 , 48 , 57 ], and thirteen (29.5%) did not report whether funding was provided [ 17 , 21 , 23 , 26 , 37 , 38 , 52 , 54 – 56 , 58 , 59 ].…”

“…Although most of the patients recruited within studies were not hospitalized due to COVID-19 infection [ 17 , 21 – 26 , 28 , 30 – 32 , 35 , 36 , 41 – 43 , 45 , 47 – 49 , 51 , 54 , 56 , 60 ], some did include patients hospitalized either for monitoring purposes or quarantine [ 18 , 19 , 33 , 52 , 55 , 57 – 59 ]. Twelve studies included a mixture of hospitalized and non hospitalized patients [ 15 , 19 , 20 , 27 , 29 , 34 , 38 – 40 , 46 , 50 , 53 ]. The majority of studies did not report data on ethnicity.…”

“…In studies that prospectively evaluated olfactory dysfunction, the timing of such evaluations varied greatly. The initial evaluations of olfaction were measured from the onset of either olfactory or general symptoms [ 15 , 20 , 25 , 26 , 28 , 31 , 43 – 45 , 53 , 60 ], from the time of positive COVID-19 test [ 16 , 21 , 23 , 33 , 34 , 38 , 45 , 46 , 57 , 59 ], from time of infection [ 24 , 51 ], during active phases of symptomatology [ 47 ], from the time of the swab [ 35 , 36 ], at initial home/clinic visit [ 27 , 30 ], at the time of admission to hospital [ 29 , 52 ], during the recovery period [ 17 , 22 ], after recovery/discharge [ 49 ], or at other specified times [ 41 , 54 , 55 ]. The timing and number of follow-up evaluations also varied amongst studies.…”

Neurological sequelae of COVID-19: a review

“…Conversely, Amer and colleagues noted that females had better recovery at 1 month from COVID-19 onset (83.9% vs. 62.5%, p < 0.005), proposing elevated androgens in males that enhance transcription of TMPRSS2 [ 56 ]. However, other studies have found no association between sex and OD/GD, making the association unclear [ 57 – 59 ]. Increased age (> 55 years) has also been associated with longer duration of GD (21.6 vs. 33.61 days, p = 0.019) [ 60 ], whereas ages > 60 years have been correlated with longer durations of OD ( p < 0.001) [ 61 ].…”