Age, degree of loss predict chemosensory recovery after COVID-19

Chemosensory loss due to the coronavirus disease 2019 (COVID-19) seems to recover partially or substantially with time, a recent study has found. Recovery is affected by age and the degree of chemosensory loss.

The researchers drew their data from the Global Consortium of Chemosensory Research (GCCR), a crowdsourced online study that looks at self-reported smell, taste, and nasal blockage, among other factors, in participants with respiratory illnesses. Survey responses from 974 patients with confirmed or suspected COVID-19 were included and assessed for chemosensory loss and recovery.

Rating scales (0–100) were used to quantify smell, taste, and chemesthesis and were compared between pre- and postdisease states. Respective mean ratings while sick with COVID-19 were 11.90±23.47, 20.39±28.07, and 40.81±32.97. After the resolution of symptoms, scores improved to 53.05±32.22, 60.75±30.89, and 69.52±25.80, respectively (p<0.001 for all).

However, such improvement was not homogenous, with two main recovery profiles emerging: partial (48.6 percent) and substantial (51.64 percent). Participants with partial recovery of chemosensation tended to be older and had been infected earlier than counterparts who achieved substantial recovery.

Clustering analysis further revealed that the degree of chemosensory loss affected the path to recovery. For instance, most patients with moderate smell/taste loss but preserved chemesthesis experienced partial recovery. On the other hand, those who had substantial loss of all three chemosensations showed the highest rate of recovery.

“Our work provides indications on the recovery process on which we shaped a scientific-based approach for healthcare professionals to characterize the clinical picture of patients reporting chemosensory loss due to COVID-19 infection,” the researchers said.