Aguilar Ticona Juan P, Nery Nivison, Hitchings Matt, Belitardo Emilia M M Andrade, Fofana Mariam O, Dorión Murilo, Victoriano Renato, Cruz Jaqueline S, Oliveira Santana Juliet, de Moraes Laise Eduarda Paixão, Cardoso Cristiane W, Ribeiro Guilherme S, Reis Mitermayer G, Khouri Ricardo, Costa Federico, Ko Albert I, Cummings Derek A T
Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
Fundação Oswaldo Cruz, Instituto Gonçalo Moniz, Ministério da Saúde, Salvador, Bahia, Brazil.
Open Forum Infect Dis. 2024 Feb 5;11(3):ofae065. doi: 10.1093/ofid/ofae065. eCollection 2024 Mar.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant has spread globally. However, the contribution of community versus household transmission to the overall risk of infection remains unclear.
Between November 2021 and March 2022, we conducted an active case-finding study in an urban informal settlement with biweekly visits across 1174 households with 3364 residents. Individuals displaying coronavirus disease 2019 (COVID-19)-related symptoms were identified, interviewed along with household contacts, and defined as index and secondary cases based on reverse-transcription polymerase chain reaction (RT-PCR) and symptom onset.
In 61 households, we detected a total of 94 RT-PCR-positive cases. Of 69 sequenced samples, 67 cases (97.1%) were attributed to the Omicron BA.1* variant. Among 35 of their households, the secondary attack rate was 50.0% (95% confidence interval [CI], 37.0%-63.0%). Women (relative risk [RR], 1.6 [95% CI, .9-2.7]), older individuals (median difference, 15 [95% CI, 2-21] years), and those reporting symptoms (RR, 1.73 [95% CI, 1.0-3.0]) had a significantly increased risk for SARS-CoV-2 secondary infection. Genomic analysis revealed substantial acquisition of viruses from the community even among households with other SARS-CoV-2 infections. After excluding community acquisition, we estimated a household secondary attack rate of 24.2% (95% CI, 11.9%-40.9%).
These findings underscore the ongoing risk of community acquisition of SARS-CoV-2 among households with current infections. The observed high attack rate necessitates swift booster vaccination, rapid testing availability, and therapeutic options to mitigate the severe outcomes of COVID-19.
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）奥密克戎变种已在全球传播。然而，社区传播与家庭传播对总体感染风险的贡献仍不明确。
2021年11月至2022年3月期间，我们在一个城市非正规住区开展了一项主动病例发现研究，每两周对1174户、3364名居民进行一次走访。识别出出现2019冠状病毒病（COVID-19）相关症状的个体，对其及其家庭接触者进行访谈，并根据逆转录聚合酶链反应（RT-PCR）和症状出现情况将其定义为索引病例和二代病例。
在61户家庭中，我们共检测到94例RT-PCR阳性病例。在69份测序样本中，67例（97.1%）归因于奥密克戎BA.1*变种。在其35户家庭中，二代发病率为50.0%（95%置信区间[CI]，37.0%-63.0%）。女性（相对风险[RR]，1.6[95%CI，0.9-2.7]）、年长者（中位数差异，15[95%CI，2-21]岁）以及报告有症状者（RR，1.73[95%CI，1.0-3.0]）感染SARS-CoV-2二代感染的风险显著增加。基因组分析显示，即使在有其他SARS-CoV-2感染的家庭中，也有大量病毒来自社区传播。排除社区传播感染后，我们估计家庭二代发病率为24.2%（95%CI，11.9%-40.9%）。
这些发现强调了在当前有感染病例的家庭中，社区传播SARS-CoV-2的持续风险。观察到的高发病率需要迅速加强疫苗接种、提供快速检测以及治疗方案，以减轻COVID-19的严重后果。
