The following examples describe where public health measures have been implemented as a result of epidemiological research, surveillance and studies:

1. John Snow (an English doctor born in 1813 and considered one of the founders of epidemiology) asked local officials to take the handle off the Broad Street water pump in London, to stop a cholera outbreak. This action was at a time when Snow was almost alone in believing that cholera was spread by water contaminated with sewage. Most believed that cholera was spread by air.

2. The Framingham Heart Study (started in 1948 in Framingham, Massachusetts, USA; ongoing: https://www.framinghamheartstudy.org/ - identified tobacco smoking and high blood lipid (cholesterol) levels as causes of heart attacks. This finding played a role in anti-smoking campaigns and the development of medicines that lower blood lipids.

3. Health departments, if confronted with an outbreak of Legionnaires disease, know from earlier research to examine sources of spread that include airborne mists and air-conditioning units.

4. One of the more recent examples deserves a more detailed description and, at the time of writing, is still ongoing: the Coronavirus disease (COVID-19) pandemic. This is a contagious disease caused by ‘severe acute respiratory syndrome coronavirus 2’ (SARS-CoV-2). The first case was identified in Wuhan, China, in December 2019. The disease has since spread worldwide, leading to an ongoing pandemic. An editorial in NATURE from January 2021 “How epidemiology has shaped the COVID pandemic” sheds light on the essential role epidemiology has played in understanding how the disease unfolded, and why, and in measures to contain and respond to COVID-19. Analyses of data on infections and deaths, and projections from studies that model the virus’s spread, have driven policy decisions all over the world. The editorial covers epidemiology’s early role in the unfolding pandemic, modelling the effectiveness of what are called non-pharmaceutical interventions such as lockdown and wearing masks, epidemiological research in new variants of the virus and new vaccines, the changing role of epidemiology as well as the challenges of how to communicate the inherent uncertainty in epidemiologists’ models and predictions.

Reading this article is highly recommended: NATURE EDITORIAL 27 January 202: