Rolling interventions for controlling COVID-19 outbreaks in the UK to reduce healthcare demand

For curbing recent outbreaks of coronavirus disease 2019 (COVID19), suppression or mitigation are two typical intervention strategies. But both strategies have their merits and limitations, and hardly achieve an optimal balance between healthcare demand and economic protection. In this paper, we designed a model to attempt to infer the impact of mitigation, suppression and multiple rolling interventions for controlling COVID-19 outbreaks in London and the UK. Our model assumed that each intervention has equivalent effect on the reproduction number R across countries and over time; where its intensity was presented by average-number contacts with susceptible individuals as infectious individuals. We considered two important features: direct link between Exposed and Recovered population, and practical healthcare demand by separation of infections into mild and critical cases. We combined the calibrated model with data on the cases of COVID-19 in London and nonLondon regions in the UK during February 2020 and March 2020 to estimate the number and distribution of infections, growth of deaths, and healthcare demand by using multiple interventions. Our results show given that multiple interventions with an intensity range, one optimal strategy was to take suppression with very high intensity in London from 23rd March for 100 days, and 3 weeks rolling intervention between very high intensity and high intensity in non-London regions. In this scenario, the total infections and deaths in the UK were limited to 2.43 million and 33.8 thousand; the peak time of healthcare demand was due to the 65th day (April 11th), where it needs hospital beds for 25.3 thousand severe and critical cases. This strategy would potentially reduce the overall infections and deaths, and delay and reduce peak healthcare demand.