Recovery from Covid-19 smell loss: Two-years of follow up

Objective: To report long-term patterns of recovery and non-recovery in a large nationwide cohort of subjects with COVID-19 associated smell loss.

Study design: Prospectively, longitudinal questionnaires.

Setting: Web-based national survey.

Methods: A longitudinal survey of adults with COVID-19 and/or sudden change in smell or taste since January 1, 2020 was launched April 10, 2020. Participants were queried again in late May 2022 regarding recovery. Data from respondents with >2 years since loss were analyzed and compared to recovery status of those more recently effected.

Results: 1103 responded to the survey of whom 946 met inclusion criteria. Among the 267 respondents for whom at least 2 years of follow up was available, 38.2 % reported full recovery, 54.3 % partial, and 7.5 % no recovery. For the entire cohort (all with ≥3 months since smell loss), 38.7 % reported complete recovery, 51.0 % reported partial recovery (ranging from mild complaints to severe phantosmia or dysosmia), and 10.3 % reported no improvement at all. Complete recovery of smell function was significantly higher in those under 40 years old (45.6 % compared to 32.9 % in those over 40).

Conclusion: Although the vast majority of subjects who do recover do so within the first 3 months, long-term spontaneous recovery can occur. Rates of recovery do not seem to differ depending on when during the pandemic the loss first occurred.