{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T06:26:40Z","timestamp":1788935200992,"version":"build-2803163510"},"reference-count":71,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2023,6,30]],"date-time":"2023-06-30T00:00:00Z","timestamp":1688083200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Shaw Foundation Hong Kong","award":["SZSM201911014"],"award-info":[{"award-number":["SZSM201911014"]}]},{"name":"Shaw Foundation Hong Kong","award":["T11\/707\/15"],"award-info":[{"award-number":["T11\/707\/15"]}]},{"name":"Michael Seak-Kan Tong","award":["SZSM201911014"],"award-info":[{"award-number":["SZSM201911014"]}]},{"name":"Michael Seak-Kan Tong","award":["T11\/707\/15"],"award-info":[{"award-number":["T11\/707\/15"]}]},{"name":"Richard Yu and Carol Yu","award":["SZSM201911014"],"award-info":[{"award-number":["SZSM201911014"]}]},{"name":"Richard Yu and Carol Yu","award":["T11\/707\/15"],"award-info":[{"award-number":["T11\/707\/15"]}]},{"name":"May Tam Mak Mei Yin","award":["SZSM201911014"],"award-info":[{"award-number":["SZSM201911014"]}]},{"name":"May Tam Mak Mei Yin","award":["T11\/707\/15"],"award-info":[{"award-number":["T11\/707\/15"]}]},{"name":"Jessie &amp; George Ho Charitable Foundation","award":["SZSM201911014"],"award-info":[{"award-number":["SZSM201911014"]}]},{"name":"Jessie &amp; George Ho Charitable Foundation","award":["T11\/707\/15"],"award-info":[{"award-number":["T11\/707\/15"]}]},{"name":"Perfect Shape Medical Limited","award":["SZSM201911014"],"award-info":[{"award-number":["SZSM201911014"]}]},{"name":"Perfect Shape Medical Limited","award":["T11\/707\/15"],"award-info":[{"award-number":["T11\/707\/15"]}]},{"name":"Respiratory Viral Research Foundation","award":["SZSM201911014"],"award-info":[{"award-number":["SZSM201911014"]}]},{"name":"Respiratory Viral Research Foundation","award":["T11\/707\/15"],"award-info":[{"award-number":["T11\/707\/15"]}]},{"name":"Hui Ming, Hui Hoy and Chow Sin Lan Charity Fund Limited","award":["SZSM201911014"],"award-info":[{"award-number":["SZSM201911014"]}]},{"name":"Hui Ming, Hui Hoy and Chow Sin Lan Charity Fund Limited","award":["T11\/707\/15"],"award-info":[{"award-number":["T11\/707\/15"]}]},{"name":"Sanming Project of Medicine in Shenzhen, China","award":["SZSM201911014"],"award-info":[{"award-number":["SZSM201911014"]}]},{"name":"Sanming Project of Medicine in Shenzhen, China","award":["T11\/707\/15"],"award-info":[{"award-number":["T11\/707\/15"]}]},{"name":"High Level-Hospital Program, Health Commission of Guangdong Province, China","award":["SZSM201911014"],"award-info":[{"award-number":["SZSM201911014"]}]},{"name":"High Level-Hospital Program, Health Commission of Guangdong Province, China","award":["T11\/707\/15"],"award-info":[{"award-number":["T11\/707\/15"]}]},{"name":"Consultancy Service for Enhancing Laboratory Surveillance of Emerging Infectious Diseases and Research Capability on Antimicrobial Resistance for the Department of Health of the Hong Kong Special Administrative Region Government, China","award":["SZSM201911014"],"award-info":[{"award-number":["SZSM201911014"]}]},{"name":"Consultancy Service for Enhancing Laboratory Surveillance of Emerging Infectious Diseases and Research Capability on Antimicrobial Resistance for the Department of Health of the Hong Kong Special Administrative Region Government, China","award":["T11\/707\/15"],"award-info":[{"award-number":["T11\/707\/15"]}]},{"name":"Research Grants Council of the Hong Kong Special Administrative Region Government, China","award":["SZSM201911014"],"award-info":[{"award-number":["SZSM201911014"]}]},{"name":"Research Grants Council of the Hong Kong Special Administrative Region Government, China","award":["T11\/707\/15"],"award-info":[{"award-number":["T11\/707\/15"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Brain Sciences"],"abstract":"<jats:p>Background: Olfactory dysfunction (OD) is a common neurosensory manifestation in long COVID. An effective and safe treatment against COVID-19-related OD is needed. Methods: This pilot trial recruited long COVID patients with persistent OD. Participants were randomly assigned to receive short-course (14 days) oral vitamin A (VitA; 25,000 IU per day) and aerosolised diffuser olfactory training (OT) thrice daily (combination), OT alone (standard care), or observation (control) for 4 weeks. The primary outcome was differences in olfactory function by butanol threshold tests (BTT) between baseline and end-of-treatment. Secondary outcomes included smell identification tests (SIT), structural MRI brain, and serial seed-based functional connectivity (FC) analyses in the olfactory cortical network by resting-state functional MRI (rs\u2013fMRI). Results: A total of 24 participants were randomly assigned to receive either combination treatment (n = 10), standard care (n = 9), or control (n = 5). Median OD duration was 157 days (IQR 127\u2013175). Mean baseline BTT score was 2.3 (SD 1.1). At end-of-treatment, mean BTT scores were significantly higher for the combination group than control (p &lt; 0.001, MD = 4.4, 95% CI 1.7 to 7.2) and standard care (p = 0.009) groups. Interval SIT scores increased significantly (p = 0.009) in the combination group. rs\u2013fMRI showed significantly higher FC in the combination group when compared to other groups. At end-of-treatment, positive correlations were found in the increased FC at left inferior frontal gyrus and clinically significant improvements in measured BTT (r = 0.858, p &lt; 0.001) and SIT (r = 0.548, p = 0.042) scores for the combination group. Conclusions: Short-course oral VitA and aerosolised diffuser OT was effective as a combination treatment for persistent OD in long COVID.<\/jats:p>","DOI":"10.3390\/brainsci13071014","type":"journal-article","created":{"date-parts":[[2023,6,30]],"date-time":"2023-06-30T16:06:37Z","timestamp":1688141197000},"page":"1014","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["A Pilot Study of Short-Course Oral Vitamin A and Aerosolised Diffuser Olfactory Training for the Treatment of Smell Loss in Long COVID"],"prefix":"10.3390","volume":"13","author":[{"given":"Tom Wai-Hin","family":"Chung","sequence":"first","affiliation":[{"name":"Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8313-0756","authenticated-orcid":false,"given":"Hui","family":"Zhang","sequence":"additional","affiliation":[{"name":"Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong, China"},{"name":"Research Institute for Intelligent Wearable Systems, The Hong Kong Polytechnic University, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6620-2479","authenticated-orcid":false,"given":"Fergus Kai-Chuen","family":"Wong","sequence":"additional","affiliation":[{"name":"Department of Ear, Nose and Throat, Pamela Youde Nethersole Eastern Hospital, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2022-8307","authenticated-orcid":false,"given":"Siddharth","family":"Sridhar","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China"},{"name":"State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China"},{"name":"Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tatia Mei-Chun","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Psychology, The University of Hong Kong, Hong Kong, China"},{"name":"State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gilberto Ka-Kit","family":"Leung","sequence":"additional","affiliation":[{"name":"Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Koon-Ho","family":"Chan","sequence":"additional","affiliation":[{"name":"Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kui-Kai","family":"Lau","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China"},{"name":"Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anthony Raymond","family":"Tam","sequence":"additional","affiliation":[{"name":"Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Deborah Tip-Yin","family":"Ho","sequence":"additional","affiliation":[{"name":"Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1765-7706","authenticated-orcid":false,"given":"Vincent Chi-Chung","family":"Cheng","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kwok-Yung","family":"Yuen","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China"},{"name":"State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China"},{"name":"Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong, China"},{"name":"The Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The University of Hong Kong, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1556-2538","authenticated-orcid":false,"given":"Ivan Fan-Ngai","family":"Hung","sequence":"additional","affiliation":[{"name":"Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong, China"},{"name":"Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China"},{"name":"The Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The University of Hong Kong, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2007-0650","authenticated-orcid":false,"given":"Henry Ka-Fung","family":"Mak","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China"},{"name":"Department of Diagnostic Radiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China"},{"name":"Alzheimer\u2019s Disease Research Network, The University of Hong Kong, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,6,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"514","DOI":"10.1016\/S0140-6736(20)30154-9","article-title":"A familial cluster of pneumonia associated with the 2019 novel coronavirus indicating person-to-person transmission: A study of a family cluster","volume":"395","author":"Chan","year":"2020","journal-title":"Lancet"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"507","DOI":"10.1080\/22221751.2021.1898291","article-title":"Lessons learned 1 year after SARS-CoV-2 emergence leading to COVID-19 pandemic","volume":"10","author":"To","year":"2021","journal-title":"Emerg. 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