{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,16]],"date-time":"2026-07-16T08:05:58Z","timestamp":1784189158143,"version":"3.55.0"},"reference-count":48,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T00:00:00Z","timestamp":1784073600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diseases"],"abstract":"<jats:p>Background\/Objectives: COVID-19 has triggered a global health crisis with sequelae extending beyond the acute phase of infection. Long COVID-19 is characterized by the persistence or new onset of symptoms weeks to months after the initial infection, including fatigue, cognitive impairment, and chemosensory dysfunction. Despite growing clinical evidence, the underlying pathophysiological mechanisms remain incompletely understood. This study aimed to evaluate the prevalence, distribution, and evolution of symptoms during the post-acute phases, with particular emphasis on olfactory and gustatory alterations. Methods: An observational study used a structured online questionnaire to collect demographic and clinical data from individuals with prior SARS-CoV-2 infection. Participants (n = 798) with persistent symptoms beyond 4\u20138 weeks were included. A subgroup of participants living in Sardinia underwent objective chemosensory assessment using the Sniffin\u2019 Sticks test and the Taste Strips test for olfactory and gustatory function, respectively. Results: A high percentage of participants reported persistent symptoms consistent with long COVID-19, including fatigue, dyspnea, cognitive impairment, and chemosensory alterations. Olfactory and gustatory dysfunctions were among the most frequent manifestations. Objective assessments confirmed the presence and severity of these deficits, in accordance with data obtained using self-reported questionnaires. Symptom profiles evolved, suggesting possible central nervous system involvement and persistent inflammatory mechanisms. Conclusions: Long COVID-19 is a complex multisystem condition with a significant impact on quality of life. Chemosensory dysfunctions may serve as useful clinical markers for patient monitoring and stratification. Integrating subjective and objective data improves diagnostic accuracy and supports the development of targeted therapeutic strategies.<\/jats:p>","DOI":"10.3390\/diseases14070256","type":"journal-article","created":{"date-parts":[[2026,7,16]],"date-time":"2026-07-16T03:34:23Z","timestamp":1784172863000},"page":"256","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Effect of Long COVID-19: Self-Reported Questionnaires and Objective Olfactory and Gustatory Evaluations"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5382-6717","authenticated-orcid":false,"given":"Ilenia","family":"Pinna","sequence":"first","affiliation":[{"name":"Department of Biomedical Sciences, University of Cagliari, SP 8 Cittadella Universitaria, 09042 Monserrato, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2982-0665","authenticated-orcid":false,"given":"Paolo","family":"Solla","sequence":"additional","affiliation":[{"name":"Department of Neurology, University of Sassari, Viale S. Pietro 10, 07100 Sassari, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gianni","family":"Orofino","sequence":"additional","affiliation":[{"name":"Department of Neurology, AOU Cagliari, University of Cagliari, SS 554 km 4.500, 09042 Cagliari, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3260-1754","authenticated-orcid":false,"given":"Tommaso","family":"Ercoli","sequence":"additional","affiliation":[{"name":"Department of Neurology, University of Sassari, Viale S. Pietro 10, 07100 Sassari, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-9653-8783","authenticated-orcid":false,"given":"Francesco","family":"Salis","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences, University of Cagliari, SP 8 Cittadella Universitaria, 09042 Monserrato, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6600-3883","authenticated-orcid":false,"given":"Francesco","family":"Loy","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences, University of Cagliari, SP 8 Cittadella Universitaria, 09042 Monserrato, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5272-8421","authenticated-orcid":false,"given":"Carla","family":"Masala","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences, University of Cagliari, SP 8 Cittadella Universitaria, 09042 Monserrato, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"536","DOI":"10.52142\/omujecm.39.2.45","article-title":"The Impact of COVID-19 on Global Health and Other Aspects of Human Life","volume":"39","author":"Kewedar","year":"2022","journal-title":"J. Exp. Clin. Med."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"m1985","DOI":"10.1136\/bmj.m1985","article-title":"Features of 20 133 UK Patients in Hospital with Covid-19 Using the ISARIC WHO Clinical Characterisation Protocol: Prospective Observational Cohort Study","volume":"369","author":"Docherty","year":"2020","journal-title":"BMJ"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Caliman-Sturdza, O.A., Gheorghita, R., and Lobiuc, A. (2025). Neuropsychiatric Manifestations of Long COVID-19: A Narrative Review of Clinical Aspects and Therapeutic Approaches. Life, 15.","DOI":"10.3390\/life15030439"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"113426","DOI":"10.1016\/j.socscimed.2020.113426","article-title":"How and Why Patients Made Long Covid","volume":"268","author":"Callard","year":"2021","journal-title":"Soc. Sci. Med."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1038\/s41579-022-00846-2","article-title":"Long COVID: Major Findings, Mechanisms and Recommendations","volume":"21","author":"Davis","year":"2023","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s10072-024-07854-5","article-title":"Neurological, Psychological, Psychosocial Complications of Long-COVID and Their Management","volume":"46","author":"Narayanan","year":"2025","journal-title":"Neurol. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"4921","DOI":"10.1007\/s10072-021-05611-6","article-title":"Qualitative Smell\/Taste Disorders as Sequelae of Acute COVID-19","volume":"42","author":"Ercoli","year":"2021","journal-title":"Neurol. Sci."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1480","DOI":"10.1007\/s11682-024-00936-0","article-title":"Neuroimaging Evaluations of Olfactory, Gustatory, and Neurological Deficits in Patients with Long-Term Sequelae of COVID-19","volume":"18","author":"Masala","year":"2024","journal-title":"Brain Imaging Behav."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"551","DOI":"10.1007\/s10787-023-01194-0","article-title":"What Is Really \u2018Long COVID\u2019?","volume":"31","author":"Szabo","year":"2023","journal-title":"Inflammopharmacology"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"736","DOI":"10.1186\/s12967-026-08149-3","article-title":"Long COVID: Deep Single-Cell Immunophenotyping and Machine Learning Reveal a General Signature for Fatigue","volume":"24","author":"Sommen","year":"2026","journal-title":"J. Transl. Med."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Chou, R., Dana, T., Ahmed, A.Y., Williams, L., Herman, E., Anderson, J., Ivlev, I., and Selph, S. (2024). Long COVID Models of Care.","DOI":"10.23970\/AHRQEPCTB45"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1093\/bmb\/ldae008","article-title":"Long COVID among Healthcare Workers: A Narrative Review of Definitions, Prevalence, Symptoms, Risk Factors and Impacts","volume":"151","author":"Dempsey","year":"2024","journal-title":"Br. Med. Bull."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Brus, I.M., Spronk, I., Haagsma, J.A., De Groot, A., Tieleman, P., Biere-Rafi, S., and Polinder, S. (2023). The Prolonged Impact of COVID-19 on Symptoms, Health-Related Quality of Life, Fatigue and Mental Well-Being: A Cross-Sectional Study. Front. Epidemiol., 3.","DOI":"10.3389\/fepid.2023.1144707"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"781","DOI":"10.1016\/j.molmed.2022.06.005","article-title":"Olfactory Dysfunction in COVID-19: Pathology and Long-Term Implications for Brain Health","volume":"28","author":"Doty","year":"2022","journal-title":"Trends Mol. Med."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2089","DOI":"10.1001\/jama.2020.6771","article-title":"Alterations in Smell or Taste in Mildly Symptomatic Outpatients with SARS-CoV-2 Infection","volume":"323","author":"Spinato","year":"2020","journal-title":"JAMA"},{"key":"ref_16","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_17","doi-asserted-by":"crossref","first-page":"2406","DOI":"10.1038\/s41591-022-02001-z","article-title":"Long-Term Neurologic Outcomes of COVID-19","volume":"28","author":"Xu","year":"2022","journal-title":"Nat. Med."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"100485","DOI":"10.1016\/j.ensci.2023.100485","article-title":"Neurological Complications after COVID-19: A Narrative Review","volume":"33","author":"Molaverdi","year":"2023","journal-title":"eNeurologicalSci"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Tai, A.P.L., Leung, M.K., Lau, B.W.M., Ngai, S.P.C., and Lau, W.K.W. (2023). Olfactory Dysfunction: A Plausible Source of COVID-19-Induced Neuropsychiatric Symptoms. Front. Neurosci., 17.","DOI":"10.3389\/fnins.2023.1156914"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Hintschich, C.A., Fischer, R., Hummel, T., Wenzel, J.J., Bohr, C., and Vielsmeier, V. (2022). Persisting Olfactory Dysfunction in Post-COVID-19 Is Associated with Gustatory Impairment: Results from Chemosensitive Testing Eight Months after the Acute Infection. PLoS ONE, 17.","DOI":"10.1371\/journal.pone.0265686"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"561","DOI":"10.1001\/archpsyc.1961.01710120031004","article-title":"An Inventory for Measuring Depression","volume":"4","author":"Beck","year":"1961","journal-title":"Arch. Gen. Psychiatry"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1093\/chemse\/22.1.39","article-title":"\u201cSniffin\u201d Sticks\u2019: Olfactory Performance Assessed by the Combined Testing of Odor Identification, Odor Discrimination and Olfactory Threshold","volume":"22","author":"Hummel","year":"1997","journal-title":"Chem. Senses."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1007\/s00405-006-0173-0","article-title":"Normative Data for the \u201cSniffin\u2019 Sticks\u201d Including Tests of Odor Identification, Odor Discrimination, and Olfactory Thresholds: An Upgrade Based on a Group of More than 3,000 Subjects","volume":"264","author":"Hummel","year":"2007","journal-title":"Eur. Arch. Otorhinolaryngol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1007\/s12078-017-9233-7","article-title":"Olfactory Function and Age: A Sniffin\u2019 Sticks Extended Test Study Performed in Sardinia","volume":"11","author":"Masala","year":"2017","journal-title":"Chemosens. Percept."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"719","DOI":"10.1007\/s00405-018-5248-1","article-title":"Updated Sniffin\u2019 Sticks Normative Data Based on an Extended Sample of 9139 Subjects","volume":"276","author":"Oleszkiewicz","year":"2019","journal-title":"Eur. Arch. Otorhinolaryngol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"242","DOI":"10.1007\/s00415-009-0088-y","article-title":"\u201ctaste Strips\u201d\u2014A Rapid, Lateralized, Gustatory Bedside Identification Test Based on Impregnated Filter Papers","volume":"256","author":"Landis","year":"2009","journal-title":"J. Neurol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"186","DOI":"10.15296\/ijwhr.2022.32","article-title":"Post-COVID-19 Menstrual Symptom Disorders Relating to Anxiety and Long COVID-19 Symptoms","volume":"10","author":"Dayican","year":"2022","journal-title":"Int. J. Womens Health Reprod. Sci."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"ckac129.139","DOI":"10.1093\/eurpub\/ckac129.139","article-title":"Long COVID: Health Symptoms, Impact on Health-Related Quality of Life and Mapping to Disability Weights","volume":"32","author":"Haagsma","year":"2022","journal-title":"Eur. J. Public Health"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"564","DOI":"10.1038\/s41380-022-01836-9","article-title":"Long-COVID Post-Viral Chronic Fatigue and Affective Symptoms Are Associated with Oxidative Damage, Lowered Antioxidant Defenses and Inflammation: A Proof of Concept and Mechanism Study","volume":"28","author":"Almulla","year":"2023","journal-title":"Mol. Psychiatry"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"691","DOI":"10.1093\/ije\/dyab239","article-title":"The COVID-19 Pandemic and the Menstrual Cycle: Research Gaps and Opportunities","volume":"51","author":"Sharp","year":"2022","journal-title":"Int. J. Epidemiol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"100268","DOI":"10.1016\/j.bbih.2021.100268","article-title":"Olfactory and Gustatory Dysfunctions in SARS-CoV-2 Infection: A Systematic Review","volume":"15","author":"Boscutti","year":"2021","journal-title":"Brain Behav. Immun.-Health"},{"key":"ref_32","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_33","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_34","doi-asserted-by":"crossref","first-page":"678","DOI":"10.23736\/S0375-9393.20.14772-2","article-title":"First Ultrastructural Autoptic Findings of SARS -Cov-2 in Olfactory Pathways and Brainstem","volume":"86","author":"Bulfamante","year":"2020","journal-title":"Minerva Anestesiol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1007\/s40629-022-00216-7","article-title":"Olfactory and Gustatory Disorders in COVID-19","volume":"31","author":"Klimek","year":"2022","journal-title":"Allergo J. Int."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Liu, X., Chiu, S.H., Tan, C.Y.R., and Chua, A.J.K. (Singap. Med. J., 2024). Long-Term Recovery from COVID-19 Olfactory and Gustatory Dysfunction: A Longitudinal Study, Singap. Med. J., ahead of print.","DOI":"10.4103\/singaporemedj.SMJ-2022-174"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"931","DOI":"10.1016\/j.cmi.2020.12.021","article-title":"Long-Term Persistence of Olfactory and Gustatory Disorders in COVID-19 Patients","volume":"27","author":"Nguyen","year":"2021","journal-title":"Clin. Microbiol. Infect."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1016\/j.anorl.2010.09.007","article-title":"Olfactory System and Emotion: Common Substrates","volume":"128","author":"Soudry","year":"2011","journal-title":"Eur. Ann. Otorhinolaryngol. Head Neck Dis."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"S376","DOI":"10.1016\/j.jval.2023.03.2111","article-title":"RWD82 To Study the Impact of Long COVID-19 in the US\u2014A 9-Month Retrospective Study","volume":"26","author":"Roy","year":"2023","journal-title":"Value Health"},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Komaroff, A.L., and Lipkin, W.I. (2023). ME\/CFS and Long COVID Share Similar Symptoms and Biological Abnormalities: Road Map to the Literature. Front. Med., 10.","DOI":"10.3389\/fmed.2023.1187163"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"722","DOI":"10.1016\/j.jinf.2022.01.024","article-title":"Persistence of Long-COVID Symptoms in a Heterogenous Prospective Cohort","volume":"84","author":"Mariani","year":"2022","journal-title":"J. Infect."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Titze-de-Almeida, R., Da Cunha, T.R., Dos Santos Silva, L.D., Ferreira, C.S., Silva, C.P., Ribeiro, A.P., De Castro Moreira Santos J\u00fanior, A., De Paula Brand\u00e3o, P.R., Silva, A.P.B., and Da Rocha, M.C.O. (2022). Persistent, New-Onset Symptoms and Mental Health Complaints in Long COVID in a Brazilian Cohort of Non-Hospitalized Patients. BMC Infect. Dis., 22.","DOI":"10.1186\/s12879-022-07065-3"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"100919","DOI":"10.1016\/j.nmni.2021.100919","article-title":"Quantitative Analysis of Taste Disorder in COVID-19 Patients, the Hypersensitivity to Salty Quality","volume":"43","author":"Asadi","year":"2021","journal-title":"New Microbes New Infect."},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Buksinska, M., Skarzynski, P.H., Raj-Koziak, D., Gos, E., and Talarek, M. (2024). Persistent Olfactory and Taste Dysfunction after COVID-19. Life, 14.","DOI":"10.3390\/life14030317"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"3325","DOI":"10.1007\/s00405-020-06590-8","article-title":"Objective Gustatory and Olfactory Dysfunction in COVID-19 Patients: A Prospective Cross-Sectional Study","volume":"278","author":"Cornelius","year":"2021","journal-title":"Eur. Arch. Otorhinolaryngol."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"bjab050","DOI":"10.1093\/chemse\/bjab050","article-title":"Corrigendum to: More Than Smell\u2014COVID-19 Is Associated with Severe Impairment of Smell, Taste, and Chemesthesis","volume":"46","author":"Parma","year":"2021","journal-title":"Chem. Senses"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"1103","DOI":"10.1002\/alr.22593","article-title":"Potential Pathogenesis of Ageusia and Anosmia in COVID-19 Patients","volume":"10","author":"Vaira","year":"2020","journal-title":"Int. Forum Allergy Rhinol."},{"key":"ref_48","first-page":"21","article-title":"Efficacy of Corticosteroid Therapy in the Treatment of Long-Lasting Olfactory Disorders in COVID-19 Patients","volume":"59","author":"Vaira","year":"2021","journal-title":"Rhinology"}],"container-title":["Diseases"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-9721\/14\/7\/256\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,16]],"date-time":"2026-07-16T07:29:23Z","timestamp":1784186963000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-9721\/14\/7\/256"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,15]]},"references-count":48,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["diseases14070256"],"URL":"https:\/\/doi.org\/10.3390\/diseases14070256","relation":{},"ISSN":["2079-9721"],"issn-type":[{"value":"2079-9721","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,15]]}}}