  Social distancing and lockdown are the two main non-pharmaceutical
interventions being used by the UK government to contain and control the
COVID-19 epidemic; these are being applied uniformly across the entire country,
even though the results of the Imperial College report by Ferguson et al show
that the impact of the infection increases sharply with age. This paper
develops a variant of the workhorse SIR model for epidemics, where the
population is classified into a number of age groups. This allows us to
understand the effects of age-dependent controls on the epidemic, and explore
possible exit strategies.
