Abstract
We study epidemiological characteristics of 25 early COVID-19 outbreak countries, which emphasizes on the reproduction of infection and effects of government control measures. The study is based on a vSIADR model which allows asymptomatic and pre-diagnosis infections to reflect COVID-19 clinical realities, and a linear mixed-effect model to analyse the association between each country’s control measures and the effective reproduction number Rt. It finds significant effects of higher stringency measures in lowering the reproduction, and a significant shortening effect on the time to the epidemic turning point by applying stronger early counter measures. Epidemic projections under scenarios of the counter measures (China and Korea, the USA and the UK) show substantial reduction in the epidemic size and death by taking earlier and forceful actions. The governments’ response before and after the start of the second wave epidemics were alarmingly weak, which made the average duration of the second wave more than doubled that of the first wave. We identify countries which urgently need to restore to at least the maximum stringency measures implemented so far in the pandemic in order to avoid even higher infection size and death.
Highlights
The Corona Virus Disease 2019 (COVID-19) caused a pandemic with more than 71 million infections and more than 1 million deaths worldwide [1] on 31 December 2020
If we focus on the first wave of the epidemics, the time to reach the epidemic turning point was much influenced by the policy implemented within the first two weeks since the date of community transmission (DCT) with a negative correlation of −0.57 (p-value 0.002), which implies the effects of the stringency measures to shorten the time to the turning point of the epidemic
Based on the varying coefficient susceptible-infected-asymptomatic-diagnosed-removed (vSIADR) model and the linear mixed-effect model (LMM), we conduct projections from 31 December 2020 to 28 February 2021 under different settings of control measures to show how the epidemics would evolve under three different strategies of policies
Summary
The Corona Virus Disease 2019 (COVID-19) caused a pandemic with more than 71 million infections and more than 1 million deaths worldwide [1] on 31 December 2020. To provide insights on the policy effects on the winter epidemic situation without vaccines, we conduct projections under different strength of control measures with the established linear mixed-effect model It shows that any relaxation of the stringency measures from the current level would lead to significant increases of infection cases and deaths by the end of February 2021. To consider the uncertainty with the underlying asymptomatic rate, two additional values of θ = 0.6 and 0.4 are employed, and the results under these two values of θ are reported in electronic supplementary material, figure S4, which shows that the estimated Rt is robust with respect to θ Another challenge in the estimation for both the conventional SEIR model and the proposed vSIADR model is due to the latent states.
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