The global impact of COVID-19 has been profound, and the public health threat it represents is the
most serious seen in a respiratory virus since the 1918 H1N1 influenza pandemic. Here we present the
results of epidemiological modelling which has informed policymaking in the UK and other countries
in recent weeks. In the absence of a COVID-19 vaccine, we assess the potential role of a number of
public health measures – so-called non-pharmaceutical interventions (NPIs) – aimed at reducing
contact rates in the population and thereby reducing transmission of the virus. In the results presented
here, we apply a previously published microsimulation model to two countries: the UK (Great Britain
specifically) and the US. We conclude that the effectiveness of any one intervention in isolation is likely
to be limited, requiring multiple interventions to be combined to have a substantial impact on
transmission.