Importance As a result of low numbers of pediatric cases early in the COVID-19 pandemic, pediatric household transmission of SARS-CoV-2 remains an understudied topic. Objective To determine whether there are differences in the odds of household transmission by younger children compared with older children. Design, Setting, and Participants This population-based cohort study took place between June 1 and December 31, 2020, in Ontario, Canada. Private households in which the index case individual of laboratory-confirmed SARS-CoV-2 infection was younger than 18 years were included. Individuals were excluded if they resided in apartments missing suite information, in households with multiple index cases, or in households where the age of the index case individual was missing. Exposures Age group of pediatric index cases categorized as 0 to 3, 4 to 8, 9 to 13, and 14 to 17 years. Main Outcomes and Measures Household transmission, defined as households where at least 1 secondary case occurred 1 to 14 days after the pediatric index case. Results A total of 6280 households had pediatric index cases, and 1717 households (27.3%) experienced secondary transmission. The mean (SD) age of pediatric index case individuals was 10.7 (5.1) years and 2863 (45.6%) were female individuals. Children aged 0 to 3 years had the highest odds of transmitting SARS-CoV-2 to household contacts compared with children aged 14 to 17 years (odds ratio, 1.43; 95% CI, 1.17-1.75). This association was similarly observed in sensitivity analyses defining secondary cases as 2 to 14 days or 4 to 14 days after the index case and stratified analyses by presence of symptoms, association with a school/childcare outbreak, or school/childcare reopening. Children aged 4 to 8 years and 9 to 13 years also had increased odds of transmission (aged 4-8 years: odds ratio, 1.40; 95% CI, 1.18-1.67; aged 9-13 years: odds ratio, 1.13; 95% CI, 0.97-1.32). Conclusions and Relevance This study suggests that younger children may be more likely to transmit SARS-CoV-2 infection compared with older children, and the highest odds of transmission was observed for children aged 0 to 3 years. Differential infectivity of pediatric age groups has implications for infection prevention within households, as well as schools/childcare, to minimize risk of household secondary transmission. Additional population-based studies are required to establish the risk of transmission by younger pediatric index cases.

中文翻译：

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年龄与 SARS-CoV-2 感染儿童家庭传播的关联。


重要性 由于在 COVID-19 大流行初期，儿科病例数量较少，因此 SARS-CoV-2 的儿科家庭传播仍然是一个未得到充分研究的话题。目的 确定年龄较小的儿童与年龄较大的儿童之间的家庭传播几率是否存在差异。设计、设置和参与者 这项基于人群的队列研究于 2020 年 6 月 1 日至 12 月 31 日在加拿大安大略省进行。实验室确诊的 SARS-CoV-2 感染指示病例年龄小于 18 岁的私人家庭也包括在内。如果个人居住在缺少套房信息的公寓、有多个指标病例的家庭或指标病例个人年龄缺失的家庭，则被排除在外。暴露 儿科指标病例的年龄组分为 0 至 3、4 至 8、9 至 13 岁和 14 至 17 岁。主要成果和措施 家庭传播，定义为在儿科指示病例发生后 1 至 14 天至少发生 1 例继发病例的家庭。结果 共有6280户家庭出现儿科指标病例，1717户（27.3%）出现二次传播。儿科指标病例的平均 (SD) 年龄为 10.7 (5.1) 岁，其中 2863 例 (45.6%) 为女性。与 14 至 17 岁的儿童相比，0 至 3 岁的儿童将 SARS-CoV-2 传播给家庭接触者的几率最高（比值比，1.43；95% CI，1.17-1.75）。在将继发病例定义为指示病例后 2 至 14 天或 4 至 14 天的敏感性分析中也观察到了这种关联，并根据症状的存在、与学校/儿童保育爆发的关联或学校/儿童保育重新开放进行分层分析。 4至8岁和9至13岁儿童的传播几率也增加（4-8岁：优势比，1.40；95% CI，1.18-1.67；9-13岁：优势比，1.13；95% CI，0.97-1.32）。结论和相关性 这项研究表明，与年龄较大的儿童相比，年龄较小的儿童可能更容易传播 SARS-CoV-2 感染，并且 0 至 3 岁儿童的传播几率最高。儿科年龄组的不同传染性对家庭以及学校/托儿所内的感染预防具有影响，以尽量减少家庭二次传播的风险。需要进行更多基于人群的研究来确定年轻儿科指标病例的传播风险。