Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), has currently infected over 6.5 million people worldwide. In response to the pandemic, numerous studies have tried to identify causes and symptoms of the disease. Emerging evidence supports recently acquired anosmia (complete loss of smell) and hyposmia (partial loss of smell) as symptoms of COVID-19, but studies of olfactory dysfunction show a wide range of prevalence, from 5% to 98%. We undertook a search of Pubmed/Medline and Google Scholar with the keywords “COVID-19,” “smell,” and/or “olfaction.” We included any study that quantified smell loss (anosmia and hyposmia) as a symptom of COVID-19. Studies were grouped and compared based on the type of method used to measure smell loss—subjective measures such as self-reported smell loss versus objective measures using rated stimuli—to determine if prevalence differed by method type. For each study, 95% confidence intervals (CIs) were calculated from point estimates of olfactory disturbances. We identified 34 articles quantifying anosmia as a symptom of COVID-19 (6 objective, 28 subjective), collected from cases identified from January 16 to April 30, 2020. The pooled prevalence estimate of smell loss was 77% when assessed through objective measurements (95% CI of 61.4-89.2%) and 44% with subjective measurements (95% CI of 32.2-57.0%). Objective measures are a more sensitive method to identify smell loss as a result of infection with SARS-CoV-2; the use of subjective measures, while expedient during the early stages of the pandemic, underestimates the true prevalence of smell loss.

中文翻译：

---

客观的感觉测试方法显示，与主观方法相比，COVID-19阳性患者的嗅觉丧失患病率更高：系统评价和荟萃分析

严重急性呼吸系统综合症冠状病毒2（SARS-CoV-2）引起2019年冠状病毒病（COVID-19），目前已感染全球650万人。为了应对这种大流行，许多研究已试图确定该疾病的原因和症状。越来越多的证据支持最近获得的厌食症（完全丧失嗅觉）和嗅觉减退（部分丧失嗅觉）作为COVID-19的症状，但是嗅觉功能障碍的研究显示患病率范围很广，从5％到98％。我们使用关键字“ COVID-19”，“气味”和/或“嗅觉”对Pubmed / Medline和Google Scholar进行了搜索。我们纳入了任何量化嗅觉丧失（失眠和低渗）作为COVID-19症状的研究。根据用于测量气味损失的方法类型（例如自我报告的气味损失等主观措施与使用额定刺激的客观措施）对研究进行分组和比较，以确定患病率是否因方法类型而异。对于每个研究，从嗅觉障碍的点估计中计算出95％的置信区间（CI）。我们从2020年1月16日至4月30日确定的病例中鉴定出34篇定量描述以AOV症状为COVID-19症状的文章（6客观，28主观）。通过客观测量评估后，嗅觉丧失的合并患病率估计为77％（ 95％CI为61.4-89.2％）和44％主观测量（95％CI为32.2-57.0％）。客观措施是识别由SARS-CoV-2感染引起的气味损失的更灵敏的方法。使用主观措施，