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LessTests Method White Paper - Overview

LessTests: Pooling Method for Rapid and Efficient SARS-CoV-2 Testing


COVID-19 was declared a global pandemic by the World Health Organization on March 11th, 2020.

Testing for the disease has since been used extensively with >1.5 billion tests carried within less than a year ( Testing is used for diagnosis as well as for epidemiological surveillance, the importance of which is highlighted by the high rates of asymptomatic and pre-symptomatic patients. The primary and gold standard method used worldwide for SARS-CoV-2 testing is based on standard real‐time quantitative PCR (RT-qPCR) amplification of one or more viral genomic regions of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from nasopharyngeal swabs. The high demand for testing kits and reagents has strained supply chains worldwide, affecting costs and availability.

Test pooling is regarded as a way to overcome challenges of cost and throughput. Pooling refers to combining multiple samples into a single test, a method that was first developed in 1943 by Robert Dorfman. In Dorfman’s two-step pooling method, each sample is present in a single pool, alongside a

fixed number of samples, and the test is performed on each pool. If a pool test result is negative, all

samples present in that pool are identified as negative to the presence of the pathogen. If a pool tests

positive, a second step of testing is needed, in which all samples present in a positive pool are retested

individually, to be identified as either negative or positive. Retests, as well as the total number of required

tests per sample, is minimized by matching the pool size to the expected prevalence. Although more

efficient and cost effective than the traditional approach, a second round of testing is always required

which delays the time in which individual results are achieved. Modern pooling approaches circumvent

these delays by assigning samples into multiple, partially overlapping pools to eliminate or reduce retests

and minimize the total number of tests altogether [7-9]. Implementing these combinatorial pooling

approaches requires defining the inherent limit of test sensitivity, algorithm refinement for various

prevalences and tolerated false-negative and false-positive rates, as well as high-throughput automated

pipelines to control pooling and resolve measurements into correct calling of positive and negative


Here, we present the LessTests pooling method - a novel, cutting-edge pooling approach. The LessTests

Analyzer applies optimized combinatorial matrices across prevalence rates in the population. This

single-step group testing algorithm enables increasing COVID-19 test efficiency by up to 12x

compression using existing laboratory setups and labware.

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