CDC COVID-19 Response, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
Clin Infect Dis. 2022 Aug 24;75(1):e122-e132. doi: 10.1093/cid/ciac125.
In Spring 2021, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.7 (Alpha) became the predominant variant in the United States. Research suggests that Alpha has increased transmissibility compared with non-Alpha lineages. We estimated household secondary infection risk (SIR), assessed characteristics associated with transmission, and compared symptoms of persons with Alpha and non-Alpha infections.
We followed households with SARS-CoV-2 infection for 2 weeks in San Diego County and metropolitan Denver, January to April 2021. We collected epidemiologic information and biospecimens for serology, reverse transcription-polymerase chain reaction (RT-PCR), and whole-genome sequencing. We stratified SIR and symptoms by lineage and identified characteristics associated with transmission using generalized estimating equations.
We investigated 127 households with 322 household contacts; 72 households (56.7%) had member(s) with secondary infections. SIRs were not significantly higher for Alpha (61.0% [95% confidence interval, 52.4-69.0%]) than non-Alpha (55.6% [44.7-65.9%], P = .49). In households with Alpha, persons who identified as Asian or Hispanic/Latino had significantly higher SIRs than those who identified as White (P = .01 and .03, respectively). Close contact (eg, kissing, hugging) with primary cases was associated with increased transmission for all lineages. Persons with Alpha infection were more likely to report constitutional symptoms than persons with non-Alpha (86.9% vs 76.8%, P = .05).
Household SIRs were similar for Alpha and non-Alpha. Comparable SIRs may be due to saturation of transmission risk in households due to extensive close contact, or true lack of difference in transmission rates. Avoiding close contact within households may reduce SARS-CoV-2 transmission for all lineages among household members.
2021 年春季，严重急性呼吸系统综合征冠状病毒 2（SARS-CoV-2）B.1.1.7（阿尔法）成为美国的主要变异株。研究表明，阿尔法变异株的传染性比非阿尔法谱系更高。我们评估了家庭二次感染风险（SIR），评估了与传播相关的特征，并比较了阿尔法和非阿尔法感染人群的症状。
2021 年 1 月至 4 月，我们在圣地亚哥县和丹佛都会区对感染了 SARS-CoV-2 的家庭进行了为期 2 周的随访。我们收集了流行病学信息和生物标本，用于血清学、逆转录聚合酶链反应（RT-PCR）和全基因组测序。我们按谱系分层 SIR 和症状，并使用广义估计方程确定与传播相关的特征。
我们调查了 127 个有 322 个家庭接触者的家庭；72 个家庭（56.7%）有成员发生二次感染。阿尔法（61.0%[95%置信区间，52.4-69.0%]）的 SIR 并不显著高于非阿尔法（55.6%[44.7-65.9%]，P=0.49）。在阿尔法家庭中，自我认同为亚洲人或西班牙裔/拉丁裔的人比自我认同为白人的人有更高的 SIR（分别为 P=0.01 和 0.03）。与主要病例的密切接触（例如亲吻、拥抱）与所有谱系的传播增加有关。感染阿尔法的人比感染非阿尔法的人更有可能报告全身症状（86.9%对 76.8%，P=0.05）。
阿尔法和非阿尔法的家庭 SIR 相似。可比的 SIR 可能是由于家庭内密切接触导致传播风险饱和，也可能是由于传播率确实没有差异。避免家庭内的密切接触可能会降低所有谱系的 SARS-CoV-2 在家属成员中的传播。
