Health Innumeracy at the Top

5 March, 2023

Dear HIFA colleagues

A recent leak of a huge cache of UK government WhatsApp messages has provided a powerful, and sobering, example of the importance of numeracy in interpreting and acting upon health information.

In August 2020, in the midst of the COVID-19 pandemic, the then UK Prime Minister Boris Johnson asked “What is the mortality rate of Covid? I have just read somewhere that it has fallen to 0.04 per cent from 0.1 per cent.” On the basis of that he wondered if the pandemic had peaked and queried the need for continuing stringent lockdown measures.

In this he had made a fundamental mathematical error – as had to be explained to him by the government’s Chief Scientific Adviser, Sir Patrick Vallance – of interpreting the figure of 0.04, which was the case fatality rate (4 per 100, or 4 percent ) as 0.04 percent. So the actual value was one hundred times greater than Johnson was assuming; the pandemic was not dramatically subsiding in the UK (indeed it was about to enter a major second wave).

(Fuller accounts, covering this and other misunderstandings and misuses of the Covid data by Johnson, can be found in recent newspaper reports e.g.

These bring to mind the wonderful book by John Allen Paulos “A Mathematician Reads the Newspapers" - which should be required reading for all journalists – and politicians!

The importance of numeracy in health care is well established (with some complexities in impact on behaviour) – see e.g. refs below. Health numeracy counts; whether it is a diabetic monitoring their own glucose levels, a healthcare worker checking the dose of a medicine, a public health official considering health risks – or a prime minister making vital decisions on health policy.

A few useful references:

Numeracy for Health (Accessed March 2023)

Ancker JS , Kaufman D. (2007) Rethinking Health Numeracy: A Multidisciplinary Literature Review, Journal of the American Medical Informatics Association, Volume 14, Issue 6, Pages 713–721,

Mulac A, Hagesaether E, Granas AG. (2022) Medication dose calculation errors and other numeracy mishaps in hospitals: Analysis of the nature and enablers of incident reports.

Journal of Advanced Nursing, 78, 224– 238.

Garcia-Retamero, R., Sobkow, A., Petrova, D., et al (2019). Numeracy and Risk Literacy: What Have We Learned so Far? The Spanish Journal of Psychology, 22, E10.

Brust-Renck PG, Nolte J, Renya VF . Numeracy in Health and Risk Messaging. Oxford Research Encyclopedias: Communication. . Published online: 24 May 2017

Lau NTT, Wilkey ED, Soltanlou M et al. (2022) Numeracy and COVID-19: examining interrelationships between numeracy, health numeracy and behaviour R. Soc. open sci.9 201303201303

Geoff Royston

HIFA profile: Geoff Royston is an Independent Health Analyst and Researcher, former Head of Strategic Analysis and Operational Research in the Department of Health for England, and Past President of the UK Operational Research Society. His work has focused on informing the design, implementation and evaluation of policies and programmes in health and social care, and on fostering the capabilities of others to work in these areas. Associated activities have included modelling for understanding the performance of complex systems, analysis and communication of risk, and horizon scanning and futures thinking. He has also worked on information and communication technology in the health sector, notably in leading the design and national launch of the telephone and online health information and advice service NHS Direct. He has served on both scientific and medical UK Research Council panels, and as an impact assessor for the UK higher education Research Excellence Framework. He is a member of the editorial board for the journal Health Care Management Science and in 2012 was Guest Editor for its special issue on Global Health. He has been a consultant for the World Health Organisation, is a long standing member of the EURO Working Group on Operational Research Applied to Health Services, and is an expert adviser to the mHIFA (mobile Healthcare Information for All) programme. He is also a member of the main HIFA Steering Group and the HIFA working group on Evaluating the Impact of Healthcare Information. geoff.royston AT