Clinical Characteristics and Long-term Symptomology of Post-COVID-19 Olfactory and Gustatory Dysfunction

Olfactory and gustatory dysfunction persists in 2-4% of patients who have recovered from COVID-19 beyond 6 months. Dysosmia (distorted smell) and dysgeusia (distorted taste) are frequently observed in the acute phase of many upper respiratory viral infections. However, persistent dysosmia in these patients is associated with persistent nasal inflammation. The purpose of this study was to determine the extent of patient self-assessed post-COVID-19 olfactory and gustatory dysfunction and to understand the quality and severity of the subjective symptoms over a year. A total of 426 registry participants were recruited to complete initial online questionnaires and follow up at three post-enrollment time points: 3 months, 6 months, 12 months. The Registry questionnaires assessed nasal inflammation (Sino-Nasal Outcome Test - SNOT-22), mental health (The Patient Health Questionnaire-2 -PHQ-2; Neuro-QoL Positive Affect and Well-Being - PAW-23), sleep quality (The Pittsburgh Sleep Quality Index - PSQI), In a cohort of 74 patients, clinical measurements of smell (Smell Identification Test (UPSIT) and taste (Waterless Taste Test (B-WETT)) were performed to validate self-reported measures of sensory impairment. Our data indicate that persistent COVID-19 olfactory and gustatory dysfunction is not associated with subjective measures of nasal inflammation. However, dryness of the nose/mouth, mood disturbance, and poor sleep quality are reported by the majority of participants. Participants struggle with detecting specific foul/dangerous odorants and tasting subtle flavors, which could have a negative effect on patient safety and well-being. Those infected during the earlier waves of the pandemic have more persistent and severe symptoms. Objective measure of both smell and taste are significantly reduced in the majority of participants with self-reported olfactory and gustatory dysfunction. Finally, standard anti-inflammatory topical and systemic therapy does not improve the subjective sense of smell while olfactory training is marginally more effective. This establishes persistent COVID19 olfactory and gustatory dysfunction as a chronic and difficult to treat syndrome resistant to standard anti-inflammatory therapy.