Eliya Timan T, Isere Elvis E, Emmana Bassey, Ugwu Chukwuebuka, Kushim Jonathan, Ishaku Precious, Ibrahim Aisha E, Bimba John S
Zankli Research Centre, Bingham University, Karu, Nasarawa State, Nigeria.
Department of Biological Sciences, Faculty of Sciences, Bingham University, Karu, Nasarawa State, Nigeria.
Afr J Lab Med. 2025 Feb 10;14(1):2514. doi: 10.4102/ajlm.v14i1.2514. eCollection 2025.
The coronavirus disease 2019 (COVID-19) pandemic strained diagnostic testing capacities globally, particularly in low- and middle-income countries like Nigeria. Reverse-transcription polymerase chain reaction (RT-PCR) remains the gold standard for COVID-19 detection, but limited testing resources caused bottlenecks in Nigeria's response during the pandemic. Sample pooling offers a cost-effective strategy to enhance testing capacity during future outbreaks.
This study determined the maximum number of COVID-19 samples that can be pooled for RT-PCR testing in Nigeria without compromising the detection sensitivity of a single positive sample.
A total of 1222 nasopharyngeal samples from symptomatic COVID-19 patients in Nasarawa State, Nigeria, collected between March 2021 and August 2022, were retrieved from the laboratory biorepository and analysed from November 2022 to February 2023. These included five positive samples with cycle threshold (Ct) values ranging from ≤ 20 to 40, and 1217 negative samples. Positive samples were pooled with negative ones at increasing dilution ratios (1:4-1:64), to assess detection sensitivity on the GeneXpert platform.
A positive sample with a Ct value ≤ 25 could be pooled with up to 64 negative samples while maintaining a detectable positive result. However, samples with Ct values of 36-40 could only be pooled with a maximum of eight negative samples. Higher Ct values reduced pooling effectiveness.
Sample pooling is a feasible method for scaling up COVID-19 RT-PCR testing in resource-limited settings like Nigeria. The Ct value is critical in determining optimal pool sizes for accurate detection.
The findings provide critical guidelines for determining the optimal pool sizes based on Ct values, aiding in effective COVID-19 testing strategies. By optimising sample pooling based on viral load, health authorities can improve their response to future COVID-19 outbreaks and similar public health emergencies.
2019年冠状病毒病（COVID-19）大流行使全球诊断检测能力不堪重负，在尼日利亚等低收入和中等收入国家尤其如此。逆转录聚合酶链反应（RT-PCR）仍然是COVID-19检测的金标准，但检测资源有限导致尼日利亚在疫情期间的应对出现瓶颈。样本合并提供了一种具有成本效益的策略，可在未来疫情爆发期间提高检测能力。
本研究确定了在不影响单个阳性样本检测灵敏度的情况下，尼日利亚可用于RT-PCR检测的COVID-19样本的最大合并数量。
从实验室生物样本库中检索了2021年3月至2022年8月期间在尼日利亚纳萨拉瓦州收集的1222份有症状COVID-19患者的鼻咽样本，并于2022年11月至2023年2月进行分析。其中包括5份阳性样本，其循环阈值（Ct）值范围为≤20至40，以及1217份阴性样本。将阳性样本与阴性样本以递增的稀释比例（1:4至1:64）合并，以评估在GeneXpert平台上的检测灵敏度。
Ct值≤25的阳性样本可与多达64份阴性样本合并，同时保持可检测的阳性结果。然而，Ct值为36 - 40的样本最多只能与8份阴性样本合并。较高的Ct值会降低合并效果。
样本合并是在尼日利亚等资源有限的环境中扩大COVID-19 RT-PCR检测规模的可行方法。Ct值对于确定准确检测的最佳合并样本量至关重要。
研究结果为基于Ct值确定最佳合并样本量提供了关键指导方针，有助于制定有效的COVID-19检测策略。通过根据病毒载量优化样本合并，卫生当局可以改善对未来COVID-19疫情及类似公共卫生紧急情况的应对。
