Modeling the COVID-19 outbreaks and the effectiveness of the containment measures adopted across countries

Edward De Brouwer; Daniele Raimondi; Yves Moreau

where t * stands for the time when the lockdown was enforced. In this text, we reported the R 0 computed with β ∞ to study the impact of the measures. When 2 or more distinct lockdowns are enforced over time, we take as β 0 the value of β at the time of lockdown of interest. We fixed 1/ω = 4 days for all countries, meaning that after a week, β reached 85% of the gap between its target and its starting value. This value is inline with the sismic and mobile data (18) . We inferred the β parameters during each period by fitting the cumulative number of cases C(t) with MCMC (Metropolis Hastings). We use a Poisson likelihood and uniform priors for β, such that β ∼ U(0, 2), and we use another uniform prior for γ, such that γ ∼ U(0.2, 1). This leads to plausible values of γ −1 between 1 and 5 days which is inline with the current estimates for the mean time elapsed between onset of symptoms and hospitalization in China (between 2.3 (12, 13) and 2.9 days (14)) and Italy (4days (22)).We inferred the β parameters during each period by fitting the cumulative number of cases C(t) with MCMC (Metropolis Hastings). We use a Poisson likelihood and uniform priors for β, such that β ∼ U(0, 2), and we use another uniform prior for γ, such that γ ∼ U(0.2, 1). This leads to plausible values of γ −1 between 1 and 5 days which is inline with the current estimates for the mean time elapsed between onset of symptoms and hospitalization in China (between 2.3 (12, 13) and 2.9 days (14)) and Italy (4days (22)). Additionally, to allow for more flexibility, we set a Gaussian prior on the initial value of the infectious pool I(0). The initial values of others pools are taken as the ones reported in the available data. We generated 10,000 samples from the posterior distribution of β and discard the first 5,000 as burnin period. For numerical integration, we used Euler with a time delta of 0.05 days. . CC-BY-NC 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.