High prevalence of long-term olfactory dysfunction confirmed by olfactory testing after a community COVID-19 outbreak

Purpose The prevalence of long-term olfactory and gustatory dysfunction in participants suffering from sudden chemosensory loss due to coronavirus disease 2019 (COVID-19) is unknown. Furthermore, evaluations of the reliability of participants' self-reporting of olfactory function (SOF) and gustatory function (SGF) using extended objective psychophysical testing are missing. Methods In this population-based cohort study in a PCR-tested community in Thuringia, Germany, olfactory function was extensively examined 4 months after a COVID-19 outbreak using the "Sniffin Sticks" test battery to determine the TDIa score, i.e., the sum of results obtained for threshold, discrimination, and identification scores averaged for both nasal sides. Gustatory function was assessed using the three-drop test resulting in the gustatory composite score (CSg). The data were compared with SOF and SGF. Results Of 43 adult convalescents (median age: 68 years; 58% female) after SARS-CoV-2 infection, 18 participants (42%) had olfactory complaints due to SOF, one participant (2%) complained of taste disturbance due to SGF. The TDIa was 22.0 +/- 5.9. Normosmia, hyposmia, and anosmia were seen in 17, 18, and eight participants, respectively. TDIa correlated with SOF (r(s) = -0.434, p = 0.004); CSg was 23.5 +/- 2.7. Normogeusia and hypogeusia were objectified in 39 and four participants, respectively. The prevalence of long-term olfactory dysfunction and gustatory dysfunction in the study group was 60.5 and 9.3%, respectively. Conclusion The SOF was reliable, especially for participants who felt a sudden chemosensory dysfunction during the outbreak. At 4 months after SARS-CoV-2 infection, a high proportion of participants were dysosmic, whereas nearly all of them had normal taste function.