Background

The SARS-CoV-2 variant B.1.1.7 was first identified in December, 2020, in England. We aimed to investigate whether increases in the proportion of infections with this variant are associated with differences in symptoms or disease course, reinfection rates, or transmissibility.

Methods

We did an ecological study to examine the association between the regional proportion of infections with the SARS-CoV-2 B.1.1.7 variant and reported symptoms, disease course, rates of reinfection, and transmissibility. Data on types and duration of symptoms were obtained from longitudinal reports from users of the COVID Symptom Study app who reported a positive test for COVID-19 between Sept 28 and Dec 27, 2020 (during which the prevalence of B.1.1.7 increased most notably in parts of the UK). From this dataset, we also estimated the frequency of possible reinfection, defined as the presence of two reported positive tests separated by more than 90 days with a period of reporting no symptoms for more than 7 days before the second positive test. The proportion of SARS-CoV-2 infections with the B.1.1.7 variant across the UK was estimated with use of genomic data from the COVID-19 Genomics UK Consortium and data from Public Health England on spike-gene target failure (a non-specific indicator of the B.1.1.7 variant) in community cases in England. We used linear regression to examine the association between reported symptoms and proportion of B.1.1.7. We assessed the Spearman correlation between the proportion of B.1.1.7 cases and number of reinfections over time, and between the number of positive tests and reinfections. We estimated incidence for B.1.1.7 and previous variants, and compared the effective reproduction number, R_t, for the two incidence estimates.

Findings

From Sept 28 to Dec 27, 2020, positive COVID-19 tests were reported by 36 920 COVID Symptom Study app users whose region was known and who reported as healthy on app sign-up. We found no changes in reported symptoms or disease duration associated with B.1.1.7. For the same period, possible reinfections were identified in 249 (0·7% [95% CI 0·6–0·8]) of 36 509 app users who reported a positive swab test before Oct 1, 2020, but there was no evidence that the frequency of reinfections was higher for the B.1.1.7 variant than for pre-existing variants. Reinfection occurrences were more positively correlated with the overall regional rise in cases (Spearman correlation 0·56–0·69 for South East, London, and East of England) than with the regional increase in the proportion of infections with the B.1.1.7 variant (Spearman correlation 0·38–0·56 in the same regions), suggesting B.1.1.7 does not substantially alter the risk of reinfection. We found a multiplicative increase in the R_t of B.1.1.7 by a factor of 1·35 (95% CI 1·02–1·69) relative to pre-existing variants. However, R_t fell below 1 during regional and national lockdowns, even in regions with high proportions of infections with the B.1.1.7 variant.

Interpretation

The lack of change in symptoms identified in this study indicates that existing testing and surveillance infrastructure do not need to change specifically for the B.1.1.7 variant. In addition, given that there was no apparent increase in the reinfection rate, vaccines are likely to remain effective against the B.1.1.7 variant.

Funding

Zoe Global, Department of Health (UK), Wellcome Trust, Engineering and Physical Sciences Research Council (UK), National Institute for Health Research (UK), Medical Research Council (UK), Alzheimer's Society.

中文翻译：

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与 SARS-CoV-2 变种 B.1.1.7 相关的症状、再感染和传播性的变化：一项生态研究

背景

SARS-CoV-2 变种 B.1.1.7 于 2020 年 12 月在英国首次发现。我们的目的是调查这种变异感染比例的增加是否与症状或病程、再感染率或传播性的差异有关。

方法

我们进行了一项生态研究，以检验 SARS-CoV-2 B.1.1.7 变体感染的区域比例与报告的症状、病程、再感染率和传播性之间的关联。有关症状类型和持续时间的数据来自 COVID 症状研究应用程序用户的纵向报告，这些用户在 2020 年 9 月 28 日至 12 月 27 日期间报告了 COVID-19 阳性检测（在此期间，B.1.1.7 的流行率增加最多）特别是在英国部分地区）。根据该数据集，我们还估计了可能再次感染的频率，定义为两次报告的阳性检测间隔超过 90 天，并且在第二次阳性检测之前报告无症状的时间超过 7 天。英国各地 B.1.1.7 变种的 SARS-CoV-2 感染比例是根据英国 COVID-19 基因组学联盟的基因组数据和英格兰公共卫生部门关于尖峰基因靶点失败的数据进行估计的（非-英格兰社区病例中 B.1.1.7 变体的具体指标。我们使用线性回归来检查报告的症状与 B.1.1.7 比例之间的关联。我们评估了随着时间的推移，B.1.1.7 病例比例与再感染数量之间以及阳性检测数量与再感染数量之间的 Spearman 相关性。我们估计了 B.1.1.7 和之前变体的发生率，并比较了两种发生率估计值的有效繁殖数 R _{t 。}

发现

2020 年 9 月 28 日至 12 月 27 日，36,920 名 COVID 症状研究应用程序用户报告了 COVID-19 检测呈阳性，这些用户所在地区已知且在应用程序注册时报告为健康。我们发现与 B.1.1.7 相关的报告症状或疾病持续时间没有变化。同一时期，在 2020 年 10 月 1 日之前报告拭子检测呈阳性的 36 509 名应用用户中，有 249 名（0·7% [95% CI 0·6–0·8]）发现了可能的再感染，但没有有证据表明，B.1.1.7 变种的再感染频率高于先前存在的变种。与 B.1.1 感染比例的区域增加相比，再感染的发生与病例总体区域增加呈更正相关（东南部、伦敦和英格兰东部的 Spearman 相关性为 0·56–0·69）。 7 变体（同一区域的 Spearman 相关性为 0·38–0·56），表明 B.1.1.7 不会显着改变再感染的风险。我们发现 B.1.1.7 的 R _t相对于先前存在的变体成倍增加 1·35 (95% CI 1·02–1·69)。然而，在地区和国家封锁期间，R _t降至 1 以下，即使是在 B.1.1.7 变种感染比例较高的地区也是如此。

解释

本研究中发现的症状没有变化表明现有的测试和监测基础设施不需要专门针对 B.1.1.7 变种进行改变。此外，鉴于再感染率没有明显增加，疫苗可能对 B.1.1.7 变种仍然有效。

资金

Zoe Global、卫生部（英国）、Wellcome Trust、工程和物理科学研究委员会（英国）、国家健康研究所（英国）、医学研究委员会（英国）、阿尔茨海默氏症协会。