Vihta Karina Doris, Pouwels Koen B, Peto Tim Ea, Pritchard Emma, House Thomas, Studley Ruth, Rourke Emma, Cook Duncan, Diamond Ian, Crook Derrick, Clifton David A, Matthews Philippa C, Stoesser Nicole, Eyre David W, Walker Ann Sarah
The National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance at the University of Oxford, Oxford, UK.
Department of Engineering, University of Oxford, Oxford, UK.
Clin Infect Dis. 2022 Aug 3;76(3):e133-41. doi: 10.1093/cid/ciac613.
The SARS-CoV-2 Delta variant has been replaced by the highly transmissible Omicron BA.1 variant, and subsequently by Omicron BA.2. It is important to understand how these changes in dominant variants affect reported symptoms, while also accounting for symptoms arising from other co-circulating respiratory viruses.
In a nationally representative UK community study, the COVID-19 Infection Survey, we investigated symptoms in PCR-positive infection episodes vs. PCR-negative study visits over calendar time, by age and vaccination status, comparing periods when the Delta, Omicron BA.1 and BA.2 variants were dominant.
Between October-2020 and April-2022, 120,995 SARS-CoV-2 PCR-positive episodes occurred in 115,886 participants, with 70,683 (58%) reporting symptoms. The comparator comprised 4,766,366 PCR-negative study visits (483,894 participants); 203,422 (4%) reporting symptoms. Symptom reporting in PCR-positives varied over time, with a marked reduction in loss of taste/smell as Omicron BA.1 dominated, maintained with BA.2 (44%/45% 17 October 2021, 16%/13% 2 January 2022, 15%/12% 27 March 2022). Cough, fever, shortness of breath, myalgia, fatigue/weakness and headache also decreased after Omicron BA.1 dominated, but sore throat increased, the latter to a greater degree than concurrent increases in PCR-negatives. Fatigue/weakness increased again after BA.2 dominated, although to a similar degree to concurrent increases in PCR-negatives. Symptoms were consistently more common in adults aged 18-65 years than in children or older adults.
Increases in sore throat (also common in the general community), and a marked reduction in loss of taste/smell, make Omicron harder to detect with symptom-based testing algorithms, with implications for institutional and national testing policies.
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）的德尔塔变种已被传播性很强的奥密克戎BA.1变种取代，随后又被奥密克戎BA.2变种取代。了解优势变种的这些变化如何影响报告的症状，同时考虑其他共同流行的呼吸道病毒引起的症状，很重要。
在一项具有全国代表性的英国社区研究——新冠病毒感染调查中，我们按年龄和疫苗接种状况，调查了在整个日历时间内，PCR检测呈阳性的感染病例与PCR检测呈阴性的研究访视中的症状，比较了德尔塔、奥密克戎BA.1和BA.2变种占主导地位的时期。
在2020年10月至2022年4月期间，115,886名参与者中发生了120,995例SARS-CoV-2 PCR检测呈阳性的病例，其中70,683例（58%）报告有症状。对照包括4,766,366次PCR检测呈阴性的研究访视（483,894名参与者）；203,422例（4%）报告有症状。PCR检测呈阳性者的症状报告随时间变化，随着奥密克戎BA.1占主导地位，味觉/嗅觉丧失明显减少，在BA.2占主导地位时保持这种情况（2021年10月17日为44%/45%，2022年1月2日为16%/13%，2022年3月27日为15%/12%）。咳嗽、发热、呼吸急促、肌痛、疲劳/虚弱和头痛在奥密克戎BA.1占主导地位后也有所减少，但喉咙痛增加，后者增加的程度大于PCR检测呈阴性者的同期增加幅度。在BA.2占主导地位后，疲劳/虚弱再次增加，不过增加程度与PCR检测呈阴性者的同期增加幅度相似。18至65岁成年人的症状始终比儿童或老年人更常见。
喉咙痛增加（在普通人群中也很常见）以及味觉/嗅觉丧失明显减少，使得基于症状的检测算法更难检测出奥密克戎变种，这对机构和国家检测政策有影响。
