Olfactory Training and Visual Stimulation Assisted by a Web-Application for Patients With Persistent Olfactory Dysfunction After SARS-CoV-2 Infection

Introduction: We aimed to quantify the benefit of olfactory training and visual stimulation assisted by a dedicated web application for patients who experienced olfactory dysfunction for ≥1 month after Sars-Cov-2 infection and compared it with published cohorts of spontaneous recoveries.Materials and MethodsWe performed a prospective observational study. Participants performed olfactory training and visual stimulation assisted by a dedicated web-application. Improvement was defined as a 2-point increase on a 10-point, self-assessed olfactory visual analogue scale.ResultsIn total, 1155 patients were assessable. Improvement was observed in patients who trained 4 weeks and 4 to 8 weeks with high concentration oils in 63.0% (58/92) and 72.9% (137/188) respectively, whereas in historical cohorts, a spontaneous improvement was observed in 7% to 27% without training respectively (p<.001). The benefit was observed regardless of the duration of the olfactory dysfunction. No or mild toxicity was reported by 86.6% (662/764) of patients. Severe toxicity leading to stop training was reported in 0.5% of patients.ConclusionsOlfactory training and visual stimulation assisted by a dedicated web application seems to accelerate olfactive improvement in persistent olfactory dysfunction following SARS-CoV-2 infection, especially after 30 days of olfactory training. Maximal duration of training appeared to be 8 weeks.