When I wrote a post on COVID-19 in February, the death toll was 425 with a total of 20,000 confirmed cases. Now, a mere six months later, the numbers have climbed to a staggering 700,000 deaths and nearly 19 million confirmed cases worldwide. While some countries have been able to slow the spread, the virus is accelerating in many regions.

Experts warn that the key to stopping the spread of the virus and reopening the global economy is testing and then isolating those that test positive before they can spread the disease to others. In hotspots, that means testing people once or twice a week as they go to and from work or school.统计“更安全的重新开放需要数百万的Covid-19每天测试。”

Testing efforts in the United States and other places have been plagued by shortages of supplies, due to the soaring demand as new hotspots develop. “The average test delay is too long,” Dr. Collins, the director of the National Institutes of Health, told该纽约时报。“这真的削弱了测试的价值，因为你做了测试，找出谁携带病毒，然后迅速让它们孤立，所以他们不会遍布它们。当建立长期延迟时，很难做到这一点。“

印度，世界第二大国家现在具有增长最快的爆发，刚刚看到上周20％的增加。“正如印度拥有世界上最低的测试率之一，所以每1000人完成约11.8个测试，那么实际的情况可能是较高的数量级。在美国，这个数字是152.98，据牛津大学我们的数据项目世界，“New York Magazine.

So, how do you test more people without using more testing supplies and lab time? Health officials are increasingly proposing pooled testing—mixing several people’s biological samples and examining them in a single test—to drastically boost the capacity without increasing the number of tests. It works best when the prevalence of the disease is low: But testing such populations in this manner can increase the availability of individual tests in hard-hit areas. According to史密森尼杂志那“Pooled testing could be the fastest and cheapest way to increase Coronavirus testing.”

池测试如何运作

有多种方法可以实现池。从大约20人的样品组合成一个池。整个池中使用了一个冠状病毒测试。如果测试回来消极，研究人员知道他们可以继续前进到另一个样本池。如果它恢复正面，那么只有那么每个人都会被测试。在下面的简化示例中，可以使用12个测试来测试27人组的组。

池测试最适合人口的大型放映，例如大学或工作场所的每周测试，因为池测试最有效的积极率。如果人口具有很高的阳性率，个人测试仍然是最好的选择。

需要考虑的另一个问题是稀释如何影响结果。“池中的标本已经被其他标本稀释，”Dr. Chris Pilcher是，旧金山加利福尼亚大学医学教授。“所以，在样本中要检测的东西的数量减少。并且这导致测试对测试的敏感性的相应降低。

“泳池测试可用于Covid的原因是病毒载荷高于足够高，即使在稀释的样品中也可以检测到。欧洲和中国的研究表明，冠状病毒的病毒载量 - 似乎在人的样品中存在多少件病毒 - 典型感染往往迅速达到高水平。“

游泳池测试研究

Professor Lakshmi Narasimhan Theagarajan, Indian Institute of Technology Palakkad, studied the efficiency of group testing for COVID-19 using polymerase chain reaction (PCR)-based testing. PCR is a method widely used to rapidly make millions to billions of copies of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it to a large enough amount to study in detail.

该study,Covid-19的小组测试：如何停止令人担忧和测试那looked at issues such as dilution. It found PCR-based testing could still perform well, but that the approach to pool testing should be modified depending on the projected rate of infection in a population. The study analyzes the benefits of different types of groupings and identifies which work best in different scenarios. For example, probabilistic group testing (PGT) works best in locations with higher infection rates, while combinatorial group testing (CGT) requires fewer tests when areas have a low infection rate.

下面的图表显示了测试的最大数量needed for different values of N (number of samples being tested) and D (number of the samples that are infected) with multi-stage testing (MST). It shows the lower the infection rate (D/N), the fewer the number of tests required. For example, if two swabs of 48 tests are positive (over 4%), the maximum number of tests to identify the two positives is 24, not the 48 tests that would be required to test all swabs individually. If the rate of infection in the population is less than 2%, the number of tests required would be further reduced.

“我们研究稀释由于群体的稀释效果，并且表明，即使在稀释效应的存在下，群体测试也可以表现良好，”Theagarajan状态也是如此。“我们提供了多个组测试算法，可以减少对Covid-19诊断所执行的测试数量。我们分析了这些测试的效率，并提供了对实际相关性的见解。利用此处描述的算法，可以开发测试计划，其能够使得测试中心能够增加在不增加PCR测试数量的情况下进行的诊断数量。

“My research is broadly in the areas of sparse data processing and statistical inference. I have been using MATLAB for almost the past 15 years mainly due to its toolboxes and in-built libraries, with which I need not reinvent the wheel, but implement my algorithms and ideas as quickly as possible; thus, giving my research a quick turnaround.”

用于生成测试计划的MATLAB代码online。

Pool testing deployed worldwide

Pool testing has been deployed in many locations around the Globe. InRwanda那they found it to be faster and more economical. Germany and Israel have implemented pool testing, and a professor from the University of Hong Kong hasproposed looking to those examplesto boost testing capabilities locally.

As more areas struggle to meet the needs of testing, pool testing may hold the key to containment.