Olfactory dysfunction in patients after recovering from COVID-19

Area of Science:

• Otolaryngology
• Infectious Diseases
• Neurology

Background:

• Smell and taste disorders are common in COVID-19 patients.
• The duration of these symptoms is not well understood.
• Few studies have used validated olfactory tests to assess COVID-19 survivors.

Purpose of the Study:

• To evaluate the olfactory function in individuals who have recovered from COVID-19.
• To use a detailed olfactory test to quantify smell impairment.
• To compare subjective smell perception with objective test results.

Main Methods:

• Included 91 patients with PCR-confirmed past COVID-19.
• Collected olfactory history via questionnaire.
• Assessed olfactory function using the Sniffin' Sticks test.
• Evaluated taste function with taste sprays.

Main Results:

• 80 patients reported sudden smell loss during COVID-19.
• At testing (approx. 8 weeks post-symptom onset), 33 patients still perceived impaired smell.
• Objective testing revealed 45.1% of patients were still hyposmic.
• Patient self-assessment of smell function poorly correlated with objective test results.

Conclusions:

• Approximately 50% of COVID-19 patients with initial smell loss experience persistent olfactory impairment two months later.
• Some patients with objective hyposmia do not subjectively notice a smell deficit.
• Further long-term studies are needed to determine if full olfactory recovery is achieved by all affected individuals.