An Extended COVID-19 Epidemiological Model with Vaccination and Multiple Interventions for Controlling COVID-19 Outbreaks in the UK
Authors: Zhang Shuhao , Bi Gaoshan , Wang Xiang , Yang Yun , Qi Jun , Li Shujun , Mao Xuxin , Peng Ruoling , Yang Po 
Published: March 2021

For controlling the first wave of the UK COVID-19 pandemic in 2020, a plethora of hypothetical COVID-19 models has been developed for simulating how diseases spread under different non-pharmaceutical interventions like suppression and mitigation and providing useful guidance to UK policymakers. While many models demonstrate their effectiveness on predicting and controlling the spread of COVID-19, they rarely consider consequence of incorporating the effects of potential SARS-CoV-2 variants and implementing vaccine interventions in large-scale. By December 2020, the second wave in the UK appeared to be much more aggressive with many more cases as one potentially more contagious SARS-CoV-2 variant was detected in the UK since September 2020. Meanwhile, UK has begun their first mass vaccination campaign on 8 December 2020, where three vaccines were in use including Pfizer, BioNTech and Moderna. Thus, these new issues pose an emergent need to build up advanced models for accessing effectiveness of taking both vaccination and multiple interventions for controlling COVID-19 outbreaks and balancing healthcare demands. Targeting at this problem, we conducted a feasibility study by defining a new mathematical model SEMCVRD (Susceptible [S], Exposed [E] (infected but asymptomatic), Mild [M] and Critical [C] (mild cases, severe and critical cases), [V] (vaccinated), Recovered [R] and Deceased [D]), containing two importantly new features: the combined infection of the mutant strain and the original strain and the addition of a new group who have been vaccinated. The model was fitted and evaluated with a public COVID-19 dataset including daily new infections, new deaths and daily vaccination in the UK from February 2020 to February 2021. Based on the simulation results, 1) we find under the assumption that the vaccine is equivalently effective against both the original strain and new variants of COVID-19, if the UK government implements insensitive suppression intervention for 13 weeks, COVID-19 epidemic will be controlled by the first week of April 2021 and nearly ended by the first week of May 2021. It shows that taking both vaccine and suppression interventions can effectively inhibit the spread and infection of the new mutant virus. 2) we suggest implementing a 3-weeks phased and progressive lifting intervention strategy up to a low intensity mitigation level for effectively controlling COVID-19 outbreaks in the UK. By implementing this strategy, the total number of infections in the UK will be limited to 4.2 million and the total number of deaths in the UK is 135 thousand, by the end of June 2021. The epidemic will nearly end in the early of June 2021, and the UK will not experience a shortage of medical resources. 3) On the assumption that UK has a capability of providing 600 thousand vaccinations every day, a 3-weeks phased and progressive lifting intervention strategy up to a moderate intensity mitigation level can end the epidemic by the end of May 2021. This strategy would reduce the overall infections and deaths of COVID-19 outbreaks, and balance healthcare demand in the UK.