Olfactory Dysfunction in Frontline Health Care Professionals During COVID-19 Pandemic in Brazil

Abstract

Upper respiratory viral infections can decrease the sense of smell either by inflammatory restriction of nasal airflow that carries the odorant molecules or through interference in olfactory sensory neuron function. During the coronavirus disease 2019 (COVID-19) pandemic, triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), worldwide reports of severe smell loss (anosmia/hyposmia) revealed a different type of olfactory dysfunction associated with respiratory virus infection. Since self-reported perception of smell is subjective and SARS-CoV-2 exposure is variable in the general population, we aimed to study a population that would be more homogeneously exposed to the virus. Here, we investigated the prevalence of olfactory loss in frontline health professionals diagnosed with COVID-19 in Brazil, one of the major epicenters of the disease. We also analyzed the rate of olfactory function recovery and the particular characteristics of olfactory deficit in this population. A widely disclosed cross-sectional online survey directed to health care workers was developed by a group of researchers to collect data concerning demographic information, general symptoms, otolaryngological symptoms, comorbidities, and COVID-19 test results. Of the 1,376 health professionals who completed the questionnaire, 795 (57.8%) were working directly with COVID-19 patients, either in intensive care units, emergency rooms, wards, outpatient clinics, or other areas. Five-hundred forty-one (39.3%) participants tested positive for SARS-CoV-2, and 509 (37%) were not tested. Prevalence of olfactory dysfunction in COVID-19-positive subjects was 83.9% (454 of 541) compared to 12.9% (42 of 326) of those who tested negative and to 14.9% (76 of 509) of those not tested. Olfactory dysfunction incidence was higher in those working in wards, emergency rooms, and intensive care units compared to professionals in outpatient clinics. In general, remission from olfactory symptoms was frequent by the time of responses. Taste disturbances were present in 74.1% of infected participants and were significantly associated with hyposmia. In conclusion, olfactory dysfunction is highly correlated with exposure to SARS-CoV-2 in health care professionals, and remission rates up to 2 weeks are high.

Keywords: COVID-19; SARS-CoV-2; anosmia; coronavirus; health care; olfaction disorders; respiratory tract infection; sense of smell.

FIGURE 1

Geo-localization of online survey participants and epidemiological data. Approximate location of respondents who enrolled in the online survey (A), indicating that the major coronavirus disease 2019 (COVID-19) hot spots in Brazil (B) are represented in the collected data (May 29, 2020 to July 8, 2020). Most of participants were from São Paulo, which has been the Brazilian epicenter.

FIGURE 2

Loss of smell is associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive testing in professionals providing health care to coronavirus disease 2019 (COVID-19) patients. Alluvial diagram depicting SARS-CoV-2-positive respondents (shades of red) as the dominant proportion of those who self-reported loss of smell, combined or not with loss of taste. A higher proportion of participants tested positive in the group providing health care to COVID-19 patients. In contrast, SARS-CoV-2-negative (shades of blue) and not-tested (green) participants reported other symptoms or no symptoms more often than SARS-CoV-2-positive respondents. Frequency and percentages of each block are reported at the top of the diagram. Correlations between individual answers are represented as flows between one block to another (each block in the same column represents a different answer for the same question). The larger the width of a flow, the larger is the number/proportion of correlated answers from different questions. Questions (Q)/answer (A) pairs were (from left to right): (1) Q – Have you been tested for COVID-19? A – Yes or no (specify test method); (2) Q – Are you feeling or have you felt any of these symptoms in the last days? / A – Answers to loss or reduction of smell or taste were aggregated as “loss of smell,” “loss of smell and taste,” “loss of taste,” “no olfactory or taste symptoms,” “no symptoms”; (3) Q – Are you providing direct care to patients with COVID-19 diagnosis? / A – Yes or no. NA: not answered.

FIGURE 3

Nasal symptoms in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected participants. Co-occurrence of different nasal symptoms (rhinorrhea, nasal obstruction, and nasal burning sensation) in SARS-CoV-2-positive (A) and SARS-CoV-2-negative or not-tested respondents (B). Age and sex are represented as violin plots for each symptom co-occurrence (top). UpSet plots depict the relationships between the symptom sets (bottom). The vertical bars represent the number of respondents who reported each one of the symptom co-occurrences. The horizontal bars shown to the left indicate the total frequencies of each individual symptom, with the red shade-filled bar denoting the sharp contrast between the frequency of hyposmia/anosmia symptoms in SARS-CoV-2-infected participants and in those who tested negative/not tested. Subjects who did not report any of the symptoms are identified as “No symptom.” Those who only reported symptoms unrelated to the nasal symptoms are identified by the dashed circles.

FIGURE 4

Duration and recovery of loss of smell and taste. Proportions based on the period of olfactory/taste function recovery are represented as stacked bar charts that depict the longer duration of loss of smell and loss of taste in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive participants. Color scale shows the duration of loss of sense and the remission status.