{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,30]],"date-time":"2025-11-30T16:16:47Z","timestamp":1764519407267,"version":"build-2065373602"},"reference-count":73,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2022,10,7]],"date-time":"2022-10-07T00:00:00Z","timestamp":1665100800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"EIT Health CoViproteHCt #20877"},{"name":"DZIF (German Center for Infection Research)"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>Persistent chemosensory dysfunction (PCD) is a common symptom of long-COVID. Chemosensory dysfunction (CD) as well as SARS-CoV-2-specific antibody levels and CD8+ T-cell immunity were investigated in a cohort of 44 healthcare workers up to a median of 721 days after a positive PCR test. CD was assessed using questionnaires and psychophysical screening tests. After 721 days, 11 of 44 (25%) participants reported PCD, with five describing an impaired quality of life. One participant reported hyperosmia (increased sense of smell). The risk of PCD at 721 days was higher for participants reporting qualitative changes (parosmia (altered smell), dysgeusia (altered taste), or phantosmia (hallucination of smell)) during initial infection than in those with isolated quantitative losses during the first COVID-19 infection (62.5% vs. 7.1%). The main recovery rate occurred within the first 100 days and did not continue until follow-up at 2 years. No correlation was found between antibody levels and CD, but we observed a trend of a higher percentage of T-cell responders in participants with CD. In conclusion, a significant proportion of patients suffer from PCD and impaired quality of life 2 years after initial infection. Qualitative changes in smell or taste during COVID-19 pose a higher risk for PCD.<\/jats:p>","DOI":"10.3390\/life12101556","type":"journal-article","created":{"date-parts":[[2022,10,9]],"date-time":"2022-10-09T01:43:11Z","timestamp":1665279791000},"page":"1556","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Two-Year Follow-Up on Chemosensory Dysfunction and Adaptive Immune Response after Infection with SARS-CoV-2 in a Cohort of 44 Healthcare Workers"],"prefix":"10.3390","volume":"12","author":[{"given":"Sophia E.","family":"Schambeck","sequence":"first","affiliation":[{"name":"Helios Klinikum Munich West, Steinerweg 5, 81241 Munich, Germany"},{"name":"Institute for Medical Microbiology, Immunology and Hygiene, School of Medicine, Technical University of Munich, Trogerstr. 30, 81675 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Laura M.","family":"Mateyka","sequence":"additional","affiliation":[{"name":"Institute for Medical Microbiology, Immunology and Hygiene, School of Medicine, Technical University of Munich, Trogerstr. 30, 81675 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Teresa","family":"Burrell","sequence":"additional","affiliation":[{"name":"Institute for Medical Microbiology, Immunology and Hygiene, School of Medicine, Technical University of Munich, Trogerstr. 30, 81675 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Natalia","family":"Graf","sequence":"additional","affiliation":[{"name":"Institute of Virology, School of Medicine, Technical University of Munich, Trogerstr. 30, 81675 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ioana","family":"Brill","sequence":"additional","affiliation":[{"name":"Helios Klinikum Munich West, Steinerweg 5, 81241 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Thomas","family":"Stark","sequence":"additional","affiliation":[{"name":"Helios Klinikum Munich West, Steinerweg 5, 81241 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9421-1911","authenticated-orcid":false,"given":"Ulrike","family":"Protzer","sequence":"additional","affiliation":[{"name":"Institute of Virology, School of Medicine, Technical University of Munich, Trogerstr. 30, 81675 Munich, Germany"},{"name":"German Center for Infection Research (DZIF), Partner Site Munich, 81675 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8713-093X","authenticated-orcid":false,"given":"Dirk H.","family":"Busch","sequence":"additional","affiliation":[{"name":"Institute for Medical Microbiology, Immunology and Hygiene, School of Medicine, Technical University of Munich, Trogerstr. 30, 81675 Munich, Germany"},{"name":"German Center for Infection Research (DZIF), Partner Site Munich, 81675 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9110-3950","authenticated-orcid":false,"given":"Markus","family":"Gerhard","sequence":"additional","affiliation":[{"name":"Institute for Medical Microbiology, Immunology and Hygiene, School of Medicine, Technical University of Munich, Trogerstr. 30, 81675 Munich, Germany"},{"name":"German Center for Infection Research (DZIF), Partner Site Munich, 81675 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Henriette","family":"Riehl","sequence":"additional","affiliation":[{"name":"Helios Klinikum Munich West, Steinerweg 5, 81241 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Holger","family":"Poppert","sequence":"additional","affiliation":[{"name":"Helios Klinikum Munich West, Steinerweg 5, 81241 Munich, Germany"},{"name":"Klinik und Poliklinik f\u00fcr Neurologie im Neuro-Kopf-Zentrum, Klinikum rechts der Isar, Ismaninger Str. 22, 81675 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,10,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"682","DOI":"10.1093\/cid\/ciaa799","article-title":"Loss of Taste and Smell as Distinguishing Symptoms of Coronavirus Disease 2019","volume":"72","author":"Dawson","year":"2020","journal-title":"Clin. Infect. Dis."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"550","DOI":"10.1016\/j.annemergmed.2020.05.015","article-title":"Acute Olfactory Loss Is Specific for COVID-19 at the Emergency Department","volume":"76","author":"Chua","year":"2020","journal-title":"Ann. Emerg. Med."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Gerkin, R.C., Ohla, K., Veldhuizen, M.G., Joseph, P.V., Kelly, C.E., Bakke, A.J., Steele, K.E., Farruggia, M.C., Pellegrino, R., and Pepino, M.Y. (2020). The best COVID-19 predictor is recent smell loss: A cross-sectional study. medRxiv.","DOI":"10.1101\/2020.07.22.20157263"},{"key":"ref_4","first-page":"574","article-title":"A review of smell and taste dysfunction in COVID-19 patients","volume":"75","author":"Wong","year":"2020","journal-title":"Med. J. Malays."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1273","DOI":"10.1002\/alr.22995","article-title":"Coronavirus disease 2019 (COVID-19)-related smell and taste impairment with widespread diffusion of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) Omicron variant","volume":"12","author":"Tirelli","year":"2022","journal-title":"Int. Forum Allergy Rhinol."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Coelho, D.H., Reiter, E.R., French, E., and Costanzo, R.M. (2022). Decreasing Incidence of Chemosensory Changes by COVID-19 Variant. Otolaryngol. Head Neck Surg., 1945998221097656.","DOI":"10.1177\/01945998221097656"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"102889","DOI":"10.1016\/j.amjoto.2020.102889","article-title":"Onset and duration of symptoms of loss of smell\/taste in patients with COVID-19: A systematic review","volume":"42","author":"Santos","year":"2021","journal-title":"Am. J. Otolaryngol."},{"key":"ref_8","first-page":"26","article-title":"Six month follow-up of self-reported loss of smell during the COVID-19 pandemic","volume":"59","author":"Hopkins","year":"2021","journal-title":"Rhinology"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"3485","DOI":"10.1007\/s00405-021-07153-1","article-title":"Long-lasting olfactory dysfunction in COVID-19 patients","volume":"279","author":"Prem","year":"2022","journal-title":"Eur. Arch. Otorhinolaryngol."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Ohla, K., Veldhuizen, M.G., Green, T., Hannum, M.E., Bakke, A.J., Moein, S.T., Tognetti, A., Postma, E.M., Pellegrino, R., and Hwang, D.L.D. (2022). A follow-up on quantitative and qualitative olfactory dysfunction and other symptoms in patients recovering from COVID-19 smell loss. Rhinology.","DOI":"10.4193\/Rhin21.415"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Schambeck, S.E., Crowell, C.S., Wagner, K.I., D\u2019Ippolito, E., Burrell, T., Mijocevic, H., Protzer, U., Busch, D.H., Gerhard, M., and Poppert, H. (2021). Phantosmia, Parosmia, and Dysgeusia Are Prolonged and Late-Onset Symptoms of COVID-19. J. Clin. Med., 10.","DOI":"10.3390\/jcm10225266"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Vaira, L.A., Gessa, C., Deiana, G., Salzano, G., Maglitto, F., Lechien, J.R., Saussez, S., Piombino, P., Biglio, A., and Biglioli, F. (2022). The Effects of Persistent Olfactory and Gustatory Dysfunctions on Quality of Life in Long-COVID-19 Patients. Life, 12.","DOI":"10.3390\/life12020141"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"889","DOI":"10.1001\/jamaoto.2022.1983","article-title":"Two-Year Prevalence and Recovery Rate of Altered Sense of Smell or Taste in Patients With Mildly Symptomatic COVID-19","volume":"148","author":"Fabbris","year":"2022","journal-title":"JAMA Otolaryngol. Head Neck Surg."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Burges Watson, D.L., Campbell, M., Hopkins, C., Smith, B., Kelly, C., and Deary, V. (2021). Altered smell and taste: Anosmia, parosmia and the impact of long COVID-19. PLoS ONE, 16.","DOI":"10.1371\/journal.pone.0256998"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1093\/chemse\/bjt072","article-title":"Olfactory disorders and quality of life--an updated review","volume":"39","author":"Croy","year":"2014","journal-title":"Chem. Senses"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1007\/s00405-004-0796-y","article-title":"Olfactory dysfunction and daily life","volume":"262","author":"Frasnelli","year":"2005","journal-title":"Eur. Arch. Otorhinolaryngol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"813","DOI":"10.1021\/acschemneuro.0c00788","article-title":"Chemosensory Systems in COVID-19: Evolution of Scientific Research","volume":"12","author":"Veronese","year":"2021","journal-title":"ACS Chem. Neurosci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"753","DOI":"10.1016\/S1474-4422(21)00182-4","article-title":"Post-viral effects of COVID-19 in the olfactory system and their implications","volume":"20","author":"Xydakis","year":"2021","journal-title":"Lancet Neurol."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Lechien, J.R., Vaira, L.A., and Saussez, S. (2022). Prevalence and 24-month recovery of olfactory dysfunction in COVID-19 patients: A multicentre prospective study. J. Intern. Med.","DOI":"10.1111\/joim.13564"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Boscolo-Rizzo, P., Tofanelli, M., Zanelli, E., Gardenal, N., and Tirelli, G. (2022). COVID-19-Related Quantitative and Qualitative Olfactory and Gustatory Dysfunction: Long-Term Prevalence and Recovery Rate. ORL J. Otorhinolaryngol. Relat. Spec., 1\u20135.","DOI":"10.1159\/000525861"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"103607","DOI":"10.1016\/j.amjoto.2022.103607","article-title":"Recovery from COVID-19 smell loss: Two-years of follow up","volume":"43","author":"McWilliams","year":"2022","journal-title":"Am. J. Otolaryngol."},{"key":"ref_22","first-page":"517","article-title":"High prevalence of long-term olfactory, gustatory, and chemesthesis dysfunction in post-COVID-19 patients: A matched case-control study with one-year follow-up using a comprehensive psychophysical evaluation","volume":"59","author":"Hummel","year":"2021","journal-title":"Rhinology"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"744","DOI":"10.1002\/alr.22923","article-title":"Self-reported olfactory and gustatory dysfunction and psychophysical testing in screening for COVID-19: A systematic review and meta-analysis","volume":"12","author":"Hoang","year":"2022","journal-title":"Int. Forum Allergy Rhinol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"110214","DOI":"10.1016\/j.celrep.2021.110214","article-title":"Recruitment of highly cytotoxic CD8(+) T cell receptors in mild SARS-CoV-2 infection","volume":"38","author":"Wagner","year":"2022","journal-title":"Cell Rep."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2245","DOI":"10.2174\/1381612822666160216150625","article-title":"Assessment of Chemosensory Function Using \u201cSniffin\u2019 Sticks\u201d, Taste Strips, Taste Sprays, and Retronasal Olfactory Tests","volume":"22","author":"Walliczek","year":"2016","journal-title":"Curr. Pharm. Des."},{"key":"ref_26","first-page":"327","article-title":"Position paper \u201cChemosensory testing for expert opinion in smell disorders\u201d","volume":"93","author":"Stuck","year":"2014","journal-title":"Laryngorhinootologie"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1601","DOI":"10.1515\/cclm-2020-0548","article-title":"Development and multicenter performance evaluation of fully automated SARS-CoV-2 IgM and IgG immunoassays","volume":"58","author":"Qian","year":"2020","journal-title":"Clin. Chem. Lab. Med."},{"key":"ref_28","unstructured":"Cohen, J. (1988). Statistical Power Analysis for the Behavioral Sciences, Lawrence Erlbaum. [2nd ed.]."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Fortunato, F., Martinelli, D., Iannelli, G., Milazzo, M., Farina, U., Di Matteo, G., De Nittis, R., Ascatigno, L., Cassano, M., and Lopalco, P.L. (2022). Self-reported olfactory and gustatory dysfunctions in COVID-19 patients: A 1-year follow-up study in Foggia district, Italy. BMC Infect. Dis., 22.","DOI":"10.1186\/s12879-022-07052-8"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"582802","DOI":"10.3389\/fmed.2020.582802","article-title":"Severity of Anosmia as an Early Symptom of COVID-19 Infection May Predict Lasting Loss of Smell","volume":"7","author":"Lechien","year":"2020","journal-title":"Front. Med."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"3702","DOI":"10.1111\/ene.14994","article-title":"Predictive factors of smell recovery in a clinical series of 288 coronavirus disease 2019 patients with olfactory dysfunction","volume":"28","author":"Saussez","year":"2021","journal-title":"Eur. J. Neurol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"e069503","DOI":"10.1136\/bmj-2021-069503","article-title":"Prognosis and persistence of smell and taste dysfunction in patients with COVID-19: Meta-analysis with parametric cure modelling of recovery curves","volume":"378","author":"Tan","year":"2022","journal-title":"BMJ"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1017\/S0022215121004047","article-title":"Delayed recovery from severe acute respiratory syndrome coronavirus-2 related anosmia predicts incomplete olfactory restoration","volume":"136","author":"Fernandez","year":"2022","journal-title":"J. Laryngol. Otol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"333","DOI":"10.1080\/00016489.2022.2062047","article-title":"Patterns of self-reported recovery from chemosensory dysfunction following SARS-CoV-2 infection: Insights after 1 year of the pandemic","volume":"142","author":"Almutairi","year":"2022","journal-title":"Acta Otolaryngol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1002\/alr.22869","article-title":"Analysis of the correlations between the severity of lung involvement and olfactory psychophysical scores in coronavirus disease 2019 (COVID-19) patients","volume":"12","author":"Amadu","year":"2022","journal-title":"Int. Forum Allergy Rhinol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"811","DOI":"10.1007\/s00405-021-06868-5","article-title":"Correlations between IL-6 serum level and olfactory dysfunction severity in COVID-19 patients: A preliminary study","volume":"279","author":"Vaira","year":"2022","journal-title":"Eur. Arch. Otorhinolaryngol."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1007\/s00405-006-0157-0","article-title":"A study on the prognostic significance of qualitative olfactory dysfunction","volume":"264","author":"Reden","year":"2007","journal-title":"Eur. Arch. Otorhinolaryngol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"596","DOI":"10.1590\/0004-282X20140109","article-title":"Hyperosmia in Lyme disease","volume":"72","author":"Puri","year":"2014","journal-title":"Arq. Neuropsiquiatr."},{"key":"ref_39","first-page":"2196","article-title":"Hyperosmia after COVID-19: Hedonic perception or hypersensitivity?","volume":"26","author":"Roccamatisi","year":"2022","journal-title":"Eur. Rev. Med. Pharmacol. Sci."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"977","DOI":"10.1177\/0333102414527014","article-title":"Olfactory function in migraine both during and between attacks","volume":"34","author":"Marmura","year":"2014","journal-title":"Cephalalgia"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"12","DOI":"10.3389\/fpsyg.2014.00012","article-title":"Hedonic appreciation and verbal description of pleasant and unpleasant odors in untrained, trainee cooks, flavorists, and perfumers","volume":"5","author":"Sezille","year":"2014","journal-title":"Front. Psychol."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1621","DOI":"10.1016\/j.mayocp.2020.05.030","article-title":"Smell and Taste Dysfunction in Patients With COVID-19: A Systematic Review and Meta-analysis","volume":"95","author":"Agyeman","year":"2020","journal-title":"Mayo Clin. Proc."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"2512","DOI":"10.1001\/jama.2020.8391","article-title":"Olfactory Dysfunction in COVID-19: Diagnosis and Management","volume":"323","author":"Whitcroft","year":"2020","journal-title":"JAMA"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"910","DOI":"10.1002\/alr.22744","article-title":"A systematic review to examine the relationship between objective and patient-reported outcome measures in sinonasal disorders: Recommendations for use in research and clinical practice","volume":"11","author":"Ta","year":"2021","journal-title":"Int. Forum Allergy Rhinol."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"1183","DOI":"10.1001\/archotol.1995.01890100087015","article-title":"Long-term follow-up of olfactory loss secondary to head trauma and upper respiratory tract infection","volume":"121","author":"Duncan","year":"1995","journal-title":"Arch. Otolaryngol. Head Neck Surg."},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Rank, A., Tzortzini, A., Kling, E., Schmid, C., Claus, R., Loll, E., Burger, R., Rommele, C., Dhillon, C., and Muller, K. (2021). One Year after Mild COVID-19: The Majority of Patients Maintain Specific Immunity, But One in Four Still Suffer from Long-Term Symptoms. J. Clin. Med., 10.","DOI":"10.3390\/jcm10153305"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"1123","DOI":"10.1017\/S0022215120002455","article-title":"Olfactory epithelium histopathological findings in long-term coronavirus disease 2019 related anosmia","volume":"134","author":"Vaira","year":"2020","journal-title":"J. Laryngol. Otol."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"108814","DOI":"10.1016\/j.clim.2021.108814","article-title":"Longitudinal observation of antibody responses for 14 months after SARS-CoV-2 infection","volume":"230","author":"Zaidi","year":"2021","journal-title":"Clin. Immunol."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"115537","DOI":"10.1016\/j.diagmicrobio.2021.115537","article-title":"Kinetics of anti-SARS-CoV-2 IgG antibody levels and potential influential factors in subjects with COVID-19: A 11-month follow-up study","volume":"101","author":"Luo","year":"2021","journal-title":"Diagn. Microbiol. Infect. Dis."},{"key":"ref_50","doi-asserted-by":"crossref","unstructured":"Lechien, J.R., Diallo, A.O., Dachy, B., Le Bon, S.D., Maniaci, A., Vaira, L.A., and Saussez, S. (2021). COVID-19: Post-vaccine Smell and Taste Disorders: Report of 6 Cases. Ear Nose Throat J., 1455613211033125.","DOI":"10.1177\/01455613211033125"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"611337","DOI":"10.3389\/fimmu.2020.611337","article-title":"Mucosal Immunity in COVID-19: A Neglected but Critical Aspect of SARS-CoV-2 Infection","volume":"11","author":"Russell","year":"2020","journal-title":"Front. Immunol."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1111\/imr.13118","article-title":"Guardians of the oral and nasopharyngeal galaxy: IgA and protection against SARS-CoV-2 infection","volume":"309","author":"Sanders","year":"2022","journal-title":"Immunol. Rev."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"1162","DOI":"10.1038\/s41467-021-21444-5","article-title":"Evolution of immune responses to SARS-CoV-2 in mild-moderate COVID-19","volume":"12","author":"Wheatley","year":"2021","journal-title":"Nat. Commun."},{"key":"ref_54","doi-asserted-by":"crossref","unstructured":"Laura, L., Dalmatin-Dragisic, M., Martinovic, K., Tutis, B., Herceg, I., Arapovic, M., and Arapovic, J. (2022). Does pre-existing immunity determine the course of SARS-CoV-2 infection in health-care workers? Single-center experience. Infection, 1\u20138.","DOI":"10.21203\/rs.3.rs-1514879\/v1"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"270","DOI":"10.1038\/s41591-020-01194-5","article-title":"T cell and antibody responses induced by a single dose of ChAdOx1 nCoV-19 (AZD1222) vaccine in a phase 1\/2 clinical trial","volume":"27","author":"Ewer","year":"2021","journal-title":"Nat. Med."},{"key":"ref_56","doi-asserted-by":"crossref","unstructured":"Lechien, J.R., Chiesa-Estomba, C.M., Vaira, L.A., Saussez, S., and Hans, S. (2020). COVID-19 Reinfection and Second Episodes of Olfactory and Gustatory Dysfunctions: Report of First Cases. Ear Nose Throat J., 145561320970105.","DOI":"10.1177\/0145561320970105"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"421","DOI":"10.1111\/joim.13259","article-title":"Clinical features of patients who had two COVID-19 episodes: A European multicentre case series","volume":"290","author":"Lechien","year":"2021","journal-title":"J. Intern. Med."},{"key":"ref_58","unstructured":"(2022, July 22). W\u00f6chentlicher Lagebericht des RKI zur Coronavirus-Krankheit-2019 (COVID-19) 14.04.2022\u2014AKTUALISIERTER STAND F\u00dcR DEUTSCHLAND. Available online: https:\/\/www.rki.de\/DE\/Content\/InfAZ\/N\/Neuartiges_Coronavirus\/Situationsberichte\/Wochenbericht\/Wochenbericht_2022-04-14.pdf?__blob=publicationFile."},{"key":"ref_59","unstructured":"(2022, July 25). W\u00f6chentlicher Lagebericht des RKI zur Coronavirus-Krankheit-2019 (COVID-19) 21.07.2022\u2014AKTUALISIERTER STAND F\u00dcR DEUTSCHLAND. Available online: https:\/\/www.rki.de\/DE\/Content\/InfAZ\/N\/Neuartiges_Coronavirus\/Situationsberichte\/Wochenbericht\/Wochenbericht_2022-07-21.pdf?__blob=publicationFile."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"2101147","DOI":"10.2807\/1560-7917.ES.2021.26.50.2101147","article-title":"Outbreak caused by the SARS-CoV-2 Omicron variant in Norway, November to December 2021","volume":"26","author":"Brandal","year":"2021","journal-title":"Euro Surveill"},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"706","DOI":"10.1038\/s41586-022-04474-x","article-title":"Altered TMPRSS2 usage by SARS-CoV-2 Omicron impacts infectivity and fusogenicity","volume":"603","author":"Meng","year":"2022","journal-title":"Nature"},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"852998","DOI":"10.3389\/fmed.2022.852998","article-title":"Is There Less Alteration of Smell Sensation in Patients With Omicron SARS-CoV-2 Variant Infection?","volume":"9","year":"2022","journal-title":"Front. Med."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"103981","DOI":"10.1016\/j.ebiom.2022.103981","article-title":"SARS-CoV-2 entry sites are present in all structural elements of the human glossopharyngeal and vagal nerves: Clinical implications","volume":"78","author":"Szalayova","year":"2022","journal-title":"EBioMedicine"},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"2520","DOI":"10.1002\/lary.28964","article-title":"Mood, Anxiety and Olfactory Dysfunction in COVID-19: Evidence of Central Nervous System Involvement?","volume":"130","author":"Speth","year":"2020","journal-title":"Laryngoscope"},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"80","DOI":"10.1016\/j.jad.2013.12.026","article-title":"Olfaction as a marker for depression in humans","volume":"160","author":"Croy","year":"2014","journal-title":"J. Affect. Disord."},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"100156","DOI":"10.1016\/j.jadr.2021.100156","article-title":"Association of COVID19-induced anosmia and ageusia with depression and suicidal ideation","volume":"5","author":"Lekkas","year":"2021","journal-title":"J. Affect. Disord. Rep."},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1002\/lary.26606","article-title":"Postinfectious olfactory loss: A retrospective study on 791 patients","volume":"128","author":"Cavazzana","year":"2018","journal-title":"Laryngoscope"},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"140419","DOI":"10.1155\/2014\/140419","article-title":"Recovery of olfactory function induces neuroplasticity effects in patients with smell loss","volume":"2014","author":"Kollndorfer","year":"2014","journal-title":"Neural Plast."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"496","DOI":"10.1002\/lary.20101","article-title":"Effects of olfactory training in patients with olfactory loss","volume":"119","author":"Hummel","year":"2009","journal-title":"Laryngoscope"},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"826","DOI":"10.1002\/lary.24340","article-title":"Olfactory training is helpful in postinfectious olfactory loss: A randomized, controlled, multicenter study","volume":"124","author":"Damm","year":"2014","journal-title":"Laryngoscope"},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"1557","DOI":"10.1007\/s00405-013-2747-y","article-title":"Olfactory training for patients with olfactory loss after upper respiratory tract infections","volume":"271","author":"Geissler","year":"2014","journal-title":"Eur. Arch. Otorhinolaryngol."},{"key":"ref_72","doi-asserted-by":"crossref","unstructured":"Pires, I.A.T., Steffens, S.T., Mocelin, A.G., Shibukawa, D.E., Leahy, L., Saito, F.L., Amadeu, N.T., Lopes, N.M.D., Garcia, E.C.D., and Albanese, M.L. (2022). Intensive Olfactory Training in Post-COVID-19 Patients: A Multicenter Randomized Clinical Trial. Am. J. Rhinol. Allergy, 19458924221113124.","DOI":"10.1177\/19458924221113124"},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"312","DOI":"10.1007\/s13365-022-01066-3","article-title":"Post-COVID-19 olfactory dysfunction: Carbamazepine as a treatment option in a series of cases","volume":"28","author":"Vasconcelos","year":"2022","journal-title":"J. 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