Quantity of tests rather than quality could be the answer to COVID-19

Rather than developing and scaling a single test that effectively tests for COVID-19, could multiple, independent tests be quicker and cheaper to develop, and just as effective? Rajesh Chandy, Academic Director of the Wheeler Institute for Business and Development was joined in conversation with Kamalini Ramdas, Professor of Management Science and Operations and Deloitte Chair in Innovation and Entrepreneurship at London Business School. 

Research published in Nature Medicine today (available at https://rdcu.be/b37a3) by Ramdas and her research colleagues –surgeon Lord Ara Darzi at Imperial and economist Dr. Sanjay Jain at Oxford – provides an opportunity for public health officials to make use of tests that don’t meet the necessary accuracy threshold by administering multiple, independently manufactured tests to each individual, to reduce the chances of an erroneous result; 

  • Multiple cheap and quick tests could meet the ‘gold-standard’ accuracy by combining tests produced by different labs, and which use different methods to detect the virus; 
  • Pooling blood samples could also speed up the rate at which populations could be tested, with optimisation models identifying how many samples to pool; 
  • Experimentation is required by those who are familiar with testing in a lab and at point of care to see if the approach works; 
  • In order to be successful, governments and healthcare systems will have to work together and share results.  

Combining tests to create a gold standard testing regime could improve diagnostic capabilities quickly and at less expense  

The global nature of the pandemic heightens the challenge of getting the number of tests that are needed to all the people who require them. There has been a well-publicised lack of accurate tests worldwide, but do Kamalini Ramdas from London Business School, and her coauthors, have a potential solution?  

The gold standard test is the RT-PCR (reverse transcription – polymerase chain reaction) test, in which a swab taken from the nose is sent to a lab to be processed. This is a highly sensitive test and is unlikely to provide a false negative, but it is also extremely expensive to process. Other, ‘point-of-care’ tests are cheaper and faster, but less accurate. These typically test for antibodies that the body is generating in response to coronavirus infection. Health systems have had issues because they have bought a huge quantity of these tests but have had to put them on hold because they are not accurate enough, providing a false negative result up to 30-50% of the time. 

There are already rapidly developed tests for antibodies that are not particularly accurate being made all over the world. These tests are being developed independently, often using different processes, so therefore you could theoretically give a patient multiple tests; since the tests are independent the chances of getting an incorrect outcome can be multiplied, which means the chance of a false negative falls dramatically. The combination of these independent tests would provide the accuracy levels of a gold-standard test.   

Many tests are being created in privately run labs by independent firms. In the short term, the goal should be for them to develop multiple independent tests, that can then be mixed and matched to create a gold standard approach.  

A quite different variant of this tactic is to pool individual samples. With this approach, 20 blood samples are taken from different people and a pooled sample is created. If the combined sample is negative, and it is a good test, then everyone is clear. If it returns a positive result, then the group is split repeatedly, using standard optimisation methods, until you find the persons who are positive. This process is already being trialled in hospitals in Germany.  

Ramdas points to an existing global database of results that is being collected by FIND (Foundation for Innovative New Diagnostics) in Geneva that reports all of the tests that are out there. This database includes details such has the target antibodies and detection process used by each test; by including each test’s accuracy, precision, and testing kit costs it could be used to generate suggestions about which regime could be more effective for different countries.  

If tests are available on Amazon, just as Amazon suggests other products based on your purchase, those looking to buy a COVID-19 test could be pushed to buy a combination of tests as a package, to improve the efficacy. Amazon could even collect data on the test results through its platform. This information could be shared with public health authorities to identify which individuals have been tested, and retested, and have found themselves to be positive.  

This could be a game-changer for developing countries who do not have the resources to fund or pay for the highly accurate tests 

Where countries have a severe constraint of a lack of time and a lack of resources, having the approach of buying multiple, cheaper tests and combining them to increase accuracy, could be the answer for health authorities. A more accurate way of testing, rather than a more accurate test, could provide a low-cost innovation that solves many of the challenges they are facing. Similarly, a pooled approach could help health authorities in developing countries test large numbers of individuals and identify where the positive tests are located without using as many resources as testing everyone separately.  


Rajesh Chandy’s conversation with Kamalini Ramdas  is part of the Wheeler Institute’s COVID-19 series – bringing together the expertise and experience of our extended community to understand, illuminate and offer solutions to the challenges created by COVID-19. Our differentiating factor is the role of business in addressing these challenges, with a focus on the implications and actions for those in developing countries.   

If you’re interested in following the Wheeler Institute COVID-19 series, check out our last episode, ‘The crisis has profound risks for Putin’s leadership, which has not been decisive or generous enough taking action against COVID-19 with Sergei Guriev.

Rajesh Chandy the Academic Director of the Wheeler Institute for Business and Development. He holds the Tony and Maureen Wheeler Chair in Entrepreneurship and is a Professor and Area Chair in the Marketing Subject Area at London Business School. He also serves as Academic Director of the Market Driving Strategies executive education course at London Business School.  

Kamalini Ramdas is Professor of Management Science and Operations; Deloitte Chair in Innovation and Entrepreneurship at London Business School.  

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