The residual effect of coronovirus disease 2019 on olfactory acuity and mucociliary clearance time: a cross-sectional, controlled study

Objective: This study evaluated the olfactory, sinonasal and mucociliary functions of patients with post-coronavirus disease 2019 long-term persistent olfactory dysfunction.

Method: Three groups of 30 patients each were formed: patients with a history of coronavirus disease 2019 infection with self-reported, persistent, sudden-onset olfactory dysfunction (group 1), patients with a history of coronavirus disease 2019 infection without any self-reported olfactory dysfunction (group 2) and healthy controls with no history of coronavirus disease 2019 infection (group 3). Saccharin time, Sniffin' Sticks, Turkish Nasal Obstruction Symptom Evaluation and Sino-Nasal Outcome Test 22 scores were compared.

Results: Turkish Nasal Obstruction Symptom Evaluation scores were similar between groups (p = 0.252). Sino-Nasal Outcome Test-22 scores were higher in group 1 than groups 2 and 3 (p < 0.01 and p < 0.001, respectively). Saccharin time was significantly longer in group 1 than groups 2 and 3 (p < 0.05 and p < 0.01, respectively). Group 1 had lower olfactory scores than groups 2 and 3 (p < 0.001 and p < 0.001, respectively).

Conclusion: Mucociliary clearance time was significantly prolonged in patients with post-coronavirus disease 2019 persistent olfactory dysfunction. Coronavirus disease 2019 infection was likely to cause asymptomatic olfactory dysfunction.