Events

Date: 26 March 2025   Time: 14:00 - 15:00

Location: Maths Lecture Theatre

We are pleased to welcome David Ellis, former member of the Combinatorics Group at QMUL, to give a talk based on his work as a member of the Action Team of DELVE (Data Evaluation & Learning for Viral Epidemics) during the Covid-19 pandemic.

All welcome. The talk will be followed by light refreshments in the Maths Common Room.

Abstract

When testing for a disease such as Covid-19 (for example, for the purposes of infection control), the standard method is individual testing: we take a sample from each individual and test these samples separately. If there are 100 individuals to test, this of course requires 100 tests.

If tests are scarce or expensive (as in the early days of the Covid-19 pandemic), it may be desirable to find ways of testing the same number of individuals using fewer tests. This can often be achieved using "pooled testing" (or "group testing"), where samples are mixed together in different pools, and those pooled samples are tested.

When the prevalence of the disease is low and the accuracy of the test is fairly high (and a small extra delay is not of critical import), pooled testing strategies can be more efficient than individual testing. For example, when disease-prevalence is around 1%, the classical pooled testing algorithm of Dorfman allows one to test 100 individuals using around 20 tests (in the average-case scenario), at the cost of having two sequential stages.

In this talk, we will discuss the mathematics of pooled testing and its uses during pandemics, in particular the Covid-19 pandemic. We will discuss the analysis of some one- and two-stage pooling strategies under imperfect tests, and we will consider the benefits, the costs, and the practical hurdles in the application of such protocols.

Speaker

David Ellis is a Reader in Pure Mathematics at the University of Bristol. He works mainly in combinatorics and related areas including links between extremal combinatorics and other areas of pure and applied mathematics.

From May 2020 he was a member of the Action Team of DELVE (Data Evaluation & Learning for Viral Epidemics); this was a multidisciplinary group convened by the Royal Society in April 2020 to inform the policy response to COVID-19.

You can find out more about David and his research on his webpage.