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At the investigated dose of AZM over 3 months, no significant benefit was found over placebo. Possible reasons could be disease severity in the investigated group, under-dosage of AZM and under-powering of the study. Therefore, more research is urgently required.

Objectives The primary aim of the study is to provide recommendations for the investigation and management of patients with new onset loss of sense of smellduring the COVID‐19 pandemic Design After undertaking a literature review, we used the RAND/UCLA methodology with a multi‐step process to reach consensus about treatment options, onward referral andimaging. Setting and participants An expert panel consisting of 15 members was assembled. A literature review was undertaken prior to the study and evidence was summarised for the panellists. Main outcome measures The panel undertook a process of ranking and classifying appropriateness of different investigations and treatment options for new onset loss of sense of smell during the COVID‐19 pandemic.Using a 9‐point Likert scale, panellists scored whether a treatment was: Not recommended, optional, or recommended. Consensus was achieved when more than 70% of responses fell into the category defined by the mean. Results Consensus was reached on the majority of statements after 2 rounds of ranking. Disagreement meant no recommendation was made regarding one treatment, using Vitamin A Drops. Alpha lipoic acid was not recommended, olfactory training was recommended for all patients with persistent loss of sense of smell of more than 2 weeks duration, and oral steroids, steroid rinses and omega 3 supplements may be considered on an individual basis. Recommendations regarding the need for referral and investigation have been made. Conclusion This study identified the appropriateness of olfactory training, different medical treatment options, referral guidelines and imaging for patients with COVID‐19 related loss of sense of smell. The guideline may evolve as our experience of COVID‐19 develops.

Whether olfaction recognizes odorants by their shape, their molecular vibrations, or both remains an open and controversial question. A convenient way to address it is to test for odor character differences between deuterated and undeuterated odorant isotopomers, since these have identical ground-state conformations but different vibrational modes. In a previous paper (Franco et al. (2011) Proc Natl Acad Sci USA 108:9, 3797-802) we showed that fruit flies can recognize the presence of deuterium in odorants by a vibrational mechanism. Here we address the question of whether humans too can distinguish deuterated and undeuterated odorants. A previous report (Keller and Vosshall (2004) Nat Neurosci 7:4, 337-8) indicated that naive subjects are incapable of distinguishing acetophenone and d-8 acetophenone. Here we confirm and extend those results to trained subjects and gas-chromatography [GC]-pure odorants. However, we also show that subjects easily distinguish deuterated and undeuterated musk odorants purified to GC-pure standard. These results are consistent with a vibrational component in human olfaction.