About 5% of people who lost smell or taste had persistent dysfunction at 6 months.

Two and a half years into the pandemic, a clearer understanding of the natural history of COVID-19–associated smell and taste dysfunction finally is emerging. Three groups have evaluated the timeline of such dysfunction.

In a meta-analysis, researchers combined data from 18 observational studies of patients with COVID-19–associated smell and taste dysfunction to determine the time course of recovery and identify risk factors for persistence. Data from 3700 patients (collected before emergence of Omicron) were included. Included studies varied widely in methodology and setting; most relied on self-report.

Key findings were:

• Among patients reporting loss of smell, the proportions who recovered by day 30, 60, 90, and 180 were 74%, 86%, 90%, and 96%, respectively.
• Among patients reporting loss of taste, the proportions who recovered by day 30, 60, 90, and 180 were 79%, 88%, 90%, and 98%, respectively.
• Persistent dysfunction in smell and taste at 6 months were reported in 5.6% and 4.4% of patients, respectively.
• Women were less likely to recover smell and taste than were men.
• Patients with nasal congestion and more-severe smell dysfunction were less likely to recover.

Comment

These results should help clinicians in counseling patients whose quality of life is affected by smell and taste dysfunction following COVID-19. However, the results are limited by lack of information on COVID-19 variants, vaccination status, and treatments received. Reassuringly, other studies from Brazil and Italy suggest that smell and taste dysfunction occur much less frequently with Omicron than with prior variants and that recovery can continue beyond 6 months.