In a new study, scientists confirmed that anosmia is an important symptom of COVID-19 in mild to moderate forms of the disease. They identified two clinical forms of this disorder. At the same time, the authors objectively did not detect a loss of smell in a third of patients complaining about it.
In about a third of patients with a complaint of loss of smell with COVID-19, scientists were unable to detect its objective signs. Also a new study published in Annals of Internal Medicine, allowed to distinguish two forms of anosmia in coronavirus infection.
Scientists analyzed the medical history of 2013 patients from 18 European countries who were outpatiently diagnosed with COVID-19 from March 22 to April 23, 2020. They interviewed all study participants to collect information about all the symptoms that are considered characteristic of this infection. The authors were interested not only in the presence of symptoms, but also in their severity.
Loss of smell was the most common symptom; 1,754 patients (87%) complained about it; 1,136 (56%) reported a loss of taste. Thus, the prevalence of such symptoms in this sample was higher than was shown in other studies.
In most patients, loss of smell developed after other symptoms appeared. At the time of the survey (discharge day or the day of the disappearance of catarrhal symptoms), the sense of smell was restored in 573 of 1754 patients. 61% of them began to smell again 4 to 14 days after the loss of smell.
Research has shown that loss of smell is not always accompanied by nasal congestion or rhinitis (inflammation in the nasal cavity). Based on this, scientists identified two forms of anosmia: accompanied and not accompanied by impaired nasal obstruction.
Scientists tested the sense of smell by objective methods in 86 study participants who complained of its loss. Anosmia (complete absence of smell) or hypoosmia (decrease in smell) were detected in more than half of them. About a third were not found objective signs of violations. The authors of the study suggest that patient complaints could be affected by news reports that anosmia is an important symptom of COVID-19. A loss or decrease in sensitivity to the four main tastes with objective examination was found in 56% of patients.
According to the authors of the study, their work confirms that the loss of smell and taste is an important diagnostic symptom of COVID-19 with mild to moderate severity of the disease.