The pandemic of Coronavirus Disease 2019 (COVID-19) has caused a vast disaster throughout the world. There is increasing evidence that olfactory dysfunction can present in COVID-19 patients. Anosmia can occur alone or can be accompanied by other symptoms of COVID-19, such as a dry cough. However, the pathogenic mechanism of olfactory dysfunction and its clinical characteristics in patients with COVID-19 remains unclear. Multiple cross-sectional studies have demonstrated that the incidence rate of olfactory dysfunction in COVID-19 patients varies from 33.9-68% with female dominance. Anosmia and dysgeusia are often comorbid in COVID-19 patients. Otolaryngologists should be mindful of the symptom of anosmia in outpatients so as not to delay the diagnosis of COVID-19. In this paper, we have reviewed the relevant knowledge based on up-to-date literature.

Journal Pre-proof the otoscope to examine the ears by oneself (Figure 2.). The children need their parents' help for examination. The patient sent the images or video taken by the smartphone via WeChat group to doctors. After got the images data, the otolaryngologists made a diagnosis and provided real-time feedback. WeChat, the Journal Pre-proof J o u r n a l P r e -p r o o f most popular social media in China, plays a critical role in telemedicine services.Since February 15, 2020, we have preliminary serviced 12 patients via SEWOAOT.There were 5 males and 7 females, with an average age of 28 years (range 4-58 years).Among them, 3 cases of acute otitis media, 2 cases of traumatic tympanic membrane perforation, 2 cases of mycotic otitis externa, 2 cases of cerumen impaction, 1 case of acute external auditory canalitis, 1 case of external auditory canal trauma, and 1 case of post-operation of external auditory canal cholesteatoma. We ask patients to rate their satisfaction with SEWOAOT ranging from dissatisfied, somewhat satisfied, and very satisfied.They were dissatisfied (0, 0%), somewhat satisfied (2, 16.7%), and very satisfied (10, 83.3%). Overall, we have received excellent feedback for participation. Mandavia et al. performed a cross-sectional study, screening ear disease in Nepal， and concluded that an SEO is a potent tool in the diagnosis of ear disease and the decision for onward referral[11]. Hakimi et al. used SEO for training medical students instead of the traditional otoscope[12]. They found that the students were more confident in identifying the anatomical landmarks of the middle ear. However, a recent study had shown that it had not proved the effectiveness of SEO when local health care workers were examining the children. It potentially relates to insufficient training and education of local medical personnel[13]. SEO in this paper offers a better imaging quality than the previous product. The device also has a directional gyroscope which can keep a constant view angle when the machine body rotates unstably. The technological progress makes it possible to Journal Pre-proof J o u r n a l P r e -p r o o f perform a self-examining. However, SEWOAOT also has disadvantages. In some remote rural areas of China, smartphone and internet use remains restricted. SEO is not convenient enough for older people. Nevertheless, SEWOAOT has great significance for preventing human cross-infection during the infectious disease outbreaks. Journal Pre-proof J o u r n a l P r e -p r o o f

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A growing body of evidence suggests that patients with the 2019 Coronavirus disease (COVID-19) have a risk of developing sudden sensorineural hearing loss (SSNHL). The pathogenesis of COVID-19-related SSNHL remains unclear. This systematic review examined whether COVID-19 causes an increased incidence of SSNHL and the clinical characteristics of patients with COVID-19-related SSNHL according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. SSNHL usually developed between a few days and 2 months after the diagnosis of COVID-19, and a proportion of patients developed it before the diagnosis of COVID-19. The literature is inconsistent regarding whether COVID-19 causes an increased incidence of SSNHL, and this matter remains unclear. This review included 23 patients with COVID-19-related SSNHL, all adult patients with an average age of 43.1 years. Of these patients, 60.9% had accompanying tinnitus symptoms. Glucocorticoids are the preferred medication to treat COVID-19-related SSNHL. Intratympanic administration may be considered to reduce the side effects of the drug. Hearing tests are suggested when hearing loss is suspected in COVID-19 individuals, and if SSNHL is detected, prompt and aggressive treatment is vital. Large-scale, multicenter research on the pathophysiology, treatment, and prognosis of COVID-19- related SSNHL should be conducted in the future.

Objectives The pandemic has affected over 182 million coronavirus disease 2019 (COVID-19) cases worldwide. Accumulated evidence indicates that anosmia is one of the significant characteristics of COVID-19 with a high prevalence. However, many aspects of COVID-19-induced anosmia are still far from being fully understood. The purpose of this review is to summarize recent developments in COVID-19-induced anosmia to increase awareness of the condition. Methods A literature search was carried out using the PubMed, Embase, Web of Science, and Scopus. We reviewed the latest literature on COVID-19-induced anosmia, including mechanisms of pathogenesis, olfactory testing, anosmia as predictive tool, pathological examinations, imaging findings, affected factors, co-existing diseases, treatments, prognosis, hypothesis theories, and future directions. Results The possible pathogenesis of COVID-19-induced anosmia may involve inflammation of the olfactory clefts and damage to the olfactory epithelium or olfactory central nervous system by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The D614G spike variant may also play a role in the increased number of anosmia patients. Anosmia may also be an essential indicator of COVID-19 spread and an early indicator of the effectiveness of political decisions. The occurrence and development of COVID-19-induced anosmia may be influenced by smoking behaviors and underlying diseases such as type 2 diabetes, gastroesophageal disorders, and rhinitis. Most patients with COVID-19-induced anosmia can fully or partially recover their olfactory function for varying durations. COVID-19-induced anosmia can be treated with various approaches such as glucocorticoids and olfactory training. Conclusion Anosmia is one of the main features of COVID-19 and the underlying disease of the patient may also influence its occurrence and development. The possible pathogenesis of COVID-19-induced anosmia is very complicated, which may involve inflammation of the olfactory clefts and damage to the olfactory epithelium or olfactory central nervous system.