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 TDI a 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 (CS g ). 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 TDI a was 22.0 ± 5.9. Normosmia, hyposmia, and anosmia were seen in 17, 18, and eight participants, respectively. TDI a correlated with SOF ( r s  = −0.434, p  = 0.004); CS g 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.