Longitudinal follow-up of taste function and trigeminal perception in COVID-19 patients with olfactory dysfunction – The COVORTS study

Background & Aims: Chemosensory dysfunction is one of the hallmarks of a COVID-19 infection. While most patients recover within a few weeks after infection, in 5–10% of the patients chemosensory dysfunction turns into a long-term problem. While olfactory loss has been extensively investigated, information regarding taste and trigeminal function has remained scarce. The COVORTS study was set up to assess the natural progression of olfactory, taste and trigeminal alterations in a prospective cohort of COVID-19 patients. Methods: We included 76 patients aged between 18-60 years old with olfactory dysfunction (>1 month) after a recent (<3 months) confirmed COVID-19 infection, and followed them for a period of 6 months. At time of inclusion (T1), 3 months (T4) and 6 months (T7) later, psychophysical testing of gustatory function was conducted (Taste Strips). Questionnaires on taste and trigeminal ability, as well as at-home self-testing of taste and trigeminal perception were performed every month. Results: We found that, subjectively, there was a large decline in taste and trigeminal functioning at baseline compared to before COVID-19 infection. Apart from salty taste, an improvement in taste and trigeminal functioning was seen over time, though not towards full recovery. The majority of patients had scores within the normative range on the Taste Strips at baseline; nonetheless, almost half of patients showed clinical improvement over time. Conclusions: Although taste and trigeminal dysfunction appear less prominent than olfactory dysfunction after COVID-19 infection, patients can and do suffer from this over a prolonged period of time. Understanding the trajectory of symptom burden and recovery from post-COVID-19 condition is essential for policy making, therapeutic interventions, and providing appropriate care and (nutritional) advice to patients.