Wits RHI, University of the Witwatersrand, Johannesburg, South Africa.
Centre for Statistical Analysis and Research, Johannesburg, South Africa.
S Afr Med J. 2024 Feb 13;114(2):e1159. doi: 10.7196/SAMJ.2024.v114i2.1159.
Patterns of SARS-CoV-2 spread have varied by geolocation, with differences in seroprevalence between urban and rural areas, and between waves. Household spread of SARS-CoV-2 is a known source of new COVID-19 infections, with rural areas in sub-Saharan Africa being more prone than urban areas to COVID-19 transmission because of limited access to water in some areas, delayed health- seeking behaviour and poor access to care.
To explore SARS-CoV-2 infection incidence and transmission in rural households in South Africa (SA).
We conducted a prospective household cluster investigation between 13 April and 21 July 2021 in the Matjhabeng subdistrict, a rural area in Free State Province, SA. Adults with SARS-CoV-2 confirmed by polymerase chain reaction (PCR) tests (index cases, ICs) and their household contacts (HCs) were enrolled. Household visits conducted at enrolment and on days 7, 14 and 28 included interviewer- administered questionnaires and respiratory and blood sample collection for SARS-CoV-2 PCR and SARS-CoV-2 immunoglobulin G serological testing, respectively. Co-primary cases were HCs with a positive SARS-CoV-2 PCR test at enrolment. The incidence rate (IR), using the Poisson distribution, was HCs with a new positive PCR and/or serological test per 1 000 person-days. Associations between outcomes and HC characteristics were adjusted for intra-cluster correlation using robust standard errors. The secondary infection rate (SIR) was the proportion of new COVID-19 infections among susceptible HCs.
Among 23 ICs and 83 HCs enrolled, 10 SARS-CoV-2 incident cases were identified, giving an IR of 5.8 per 1 000 person-days (95% confidence interval (CI) 3.14 - 11.95). Households with a co-primary case had higher IRs than households without a co-primary case (crude IR 14.16 v. 1.75, respectively; p=0.054). HIV infection, obesity and the presence of chronic conditions did not materially alter the crude IR. The SIR was 15.9% (95% CI 7.90 - 29.32). Households with a lower household density (fewer household members per bedroom) had a higher IR (IR 9.58; 95% CI 4.67 - 21.71) than households with a higher density (IR 3.06; 95% CI 1.00 - 12.35).
We found a high SARS-CoV-2 infection rate among HCs in a rural setting, with 48% of households having a co-primary case at the time of enrolment. Households with co-primary cases were associated with a higher seroprevalence and incidence of SARS-CoV-2. Sociodemographic and health characteristics were not associated with SARS-CoV-2 transmission in this study, and we did not identify any transmission risks inherent to a rural setting.
SARS-CoV-2 的传播模式因地理位置而异，城乡之间的血清阳性率存在差异，且存在波峰和波谷。家庭传播是 SARS-CoV-2 新感染的已知来源，由于撒哈拉以南非洲部分地区供水有限、就医行为延迟以及获得医疗服务的机会有限，农村地区比城市地区更容易发生 COVID-19 传播。
探索南非农村家庭中 SARS-CoV-2 的感染发生率和传播情况。
我们于 2021 年 4 月 13 日至 7 月 21 日在南非自由州省马杰哈本地区开展了一项前瞻性家庭集群调查。PCR 检测（索引病例，ICs）确认 SARS-CoV-2 阳性的成年人及其家庭接触者（HCs）纳入研究。在登记时以及第 7、14 和 28 天进行家庭访问，包括由调查员进行的问卷调查以及呼吸道和血液样本采集，用于 SARS-CoV-2 PCR 和 SARS-CoV-2 免疫球蛋白 G 血清学检测。共同主要病例为登记时 SARS-CoV-2 PCR 检测阳性的 HCs。采用泊松分布计算新阳性 PCR 和/或血清学检测的每 1000 人日感染率（IR）。使用稳健标准误差，根据群内相关性调整结局与 HCs 特征之间的相关性。二级感染率（SIR）是易感 HCs 中新发生 COVID-19 感染的比例。
在 23 名 IC 和 83 名 HCs 中，发现 10 例 SARS-CoV-2 新发病例，感染率为 5.8/1000 人日（95%CI：3.14-11.95）。有共同主要病例的家庭的 IR 高于没有共同主要病例的家庭（未经校正的 IR 分别为 14.16 和 1.75；p=0.054）。HIV 感染、肥胖和慢性疾病的存在并未显著改变未经校正的 IR。SIR 为 15.9%（95%CI：7.90-29.32）。家庭密度较低（每个卧室的家庭成员较少）的家庭的 IR 较高（IR 9.58；95%CI：4.67-21.71），而家庭密度较高的家庭的 IR 较低（IR 3.06；95%CI：1.00-12.35）。
我们发现农村地区的 HCs 中 SARS-CoV-2 感染率较高，48%的家庭在登记时就有共同主要病例。有共同主要病例的家庭与更高的 SARS-CoV-2 血清阳性率和发病率相关。在这项研究中，社会人口学和健康特征与 SARS-CoV-2 的传播无关，我们也没有发现农村地区固有的任何传播风险。
