[3] In 1987 she received her PhD from Imperial College, London with a thesis on Mathematical models of the epidemiology of measles in developing countries, supervised by Roy M.

[8][3][9] McLean's research interests are in the use of mathematical models to aid our understanding of the evolution and spread of infectious agents.

The review, chaired by Sir Brian Follett, made recommendations from a scientific standpoint about how to prevent and combat further invasions of highly infectious livestock diseases.

[14] From 2013 onwards McLean was involved in the restatement or synthesis of scientific evidence on key topic areas for policy.

Together with Professor Graham Medley she co-chaired the SAGE sub-committee Scientific Pandemic Influenza Group on Modelling (SPI-M-O).

[21] In 2023 the Cabinet Secretary announced that McLean had been selected by the Prime Minister as the new Government Chief Scientific Adviser after an open competition, to succeed Sir Patrick Vallance.