Importance Data about the risk of SARS-CoV-2 infection among children compared with adults are needed to inform COVID-19 risk communication and prevention strategies, including COVID-19 vaccination policies for children. Objective To compare incidence rates and clinical characteristics of SARS-CoV-2 infection among adults and children and estimated household infection risks within a prospective household cohort. Design, Setting, and Participants Households with at least 1 child aged 0 to 17 years in selected counties in Utah and New York City, New York, were eligible for enrollment. From September 2020 through April 2021, participants self-collected midturbinate nasal swabs for reverse transcription-polymerase chain reaction testing for SARS-CoV-2 and responded to symptom questionnaires each week. Participants also self-collected additional respiratory specimens with onset of COVID-19-like illness. For children unable to self-collect respiratory specimens, an adult caregiver collected the specimens. Main Outcomes and Measures The primary outcome was incident cases of any SARS-CoV-2 infection, including asymptomatic and symptomatic infections. Additional measures were the asymptomatic fraction of infection calculated by dividing incidence rates of asymptomatic infection by rates of any infection, clinical characteristics of infection, and household infection risks. Primary outcomes were compared by participant age group. Results A total of 1236 participants in 310 households participated in surveillance, including 176 participants (14%) who were aged 0 to 4 years, 313 (25%) aged 5 to 11 years, 163 (13%) aged 12 to 17 years, and 584 (47%) 18 years or older. Overall incidence rates of SARS-CoV-2 infection were 3.8 (95% CI, 2.4-5.9) and 7.7 (95% CI, 4.1-14.5) per 1000 person-weeks among the Utah and New York City cohorts, respectively. Site-adjusted incidence rates per 1000 person-weeks were similar by age group: 6.3 (95% CI, 3.6-11.0) for children 0 to 4 years, 4.4 (95% CI, 2.5-7.5) for children 5 to 11 years, 6.0 (95% CI, 3.0-11.7) for children 12 to 17 years, and 5.1 (95% CI, 3.3-7.8) for adults (≥18 years). The asymptomatic fractions of infection by age group were 52%, 50%, 45%, and 12% among individuals aged 0 to 4 years, 5 to 11 years, 12 to 17 years, and 18 years or older, respectively. Among 40 households with 1 or more SARS-CoV-2 infections, the mean risk of SARS-CoV-2 infection among all enrolled household members was 52% (range, 11%-100%), with higher risks in New York City compared with Utah (80% [95% CI, 64%-91%] vs 44% [95% CI, 36%-53%]; P < .001). Conclusions and Relevance In this study, children had similar incidence rates of SARS-CoV-2 infection compared with adults, but a larger proportion of infections among children were asymptomatic.

中文翻译：

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犹他州和纽约州纽约市儿童和成人感染 SARS-CoV-2 的发病率、家庭感染风险和临床特征。

需要有关儿童与成人相比感染 SARS-CoV-2 的风险的数据，以告知 COVID-19 风险沟通和预防策略，包括针对儿童的 COVID-19 疫苗接种政策。目的 比较成人和儿童 SARS-CoV-2 感染的发病率和临床特征，并估计前瞻性家庭队列中的家庭感染风险。设计、设置和参与者 在犹他州和纽约州纽约市的选定县中至少有 1 名 0 至 17 岁儿童的家庭有资格参加。从 2020 年 9 月到 2021 年 4 月，参与​​者每周自行收集中鼻甲鼻拭子用于 SARS-CoV-2 的逆转录-聚合酶链反应检测，并回答症状问卷。参与者还自行收集了出现 COVID-19 样疾病的其他呼吸道标本。对于无法自行采集呼吸道标本的儿童，由成年护理人员采集标本。主要成果和措施 主要成果是任何 SARS-CoV-2 感染的事件病例，包括无症状和有症状的感染。其他措施是通过将无症状感染的发生率除以任何感染率​​、感染的临床特征和家庭感染风险来计算的无症状感染分数。主要结果按参与者年龄组进行比较。结果 共有310户1236人参与监测，其中0~4岁176人（14%），5~11岁313人（25%），12~17岁163人（13%），584 人 (47%) 年满 18 岁。在犹他州和纽约市队列中，SARS-CoV-2 感染的总发病率分别为每 1000 人每周 3.8（95% CI，2.4-5.9）和 7.7（95% CI，4.1-14.5）。按年龄组划分的每 1000 人周的现场调整发病率相似：0 至 4 岁儿童为 6.3（95% CI，3.6-11.0），5 至 11 岁儿童为 4.4（95% CI，2.5-7.5）， 12 至 17 岁儿童为 6.0（95% CI，3.0-11.7），成人（≥18 岁）为 5.1（95% CI，3.3-7.8）。按年龄组划分的无症状感染比例在 0 至 4 岁、5 至 11 岁、12 至 17 岁和 18 岁或以上的个体中分别为 52%、50%、45% 和 12%。在感染 1 次或多次 SARS-CoV-2 的 40 个家庭中，所有登记的家庭成员感染 SARS-CoV-2 的平均风险为 52%（范围，11%-100%），与犹他州相比，纽约市的风险更高（80% [95% CI, 64%-91%] vs 44% [95% CI, 36%-53%]；P < .001）。结论和相关性 在这项研究中，儿童的 SARS-CoV-2 感染发生率与成人相似，但儿童中无症状感染的比例更大。