Using a system of time-dynamical equations, we investigate how daily mobility indices, such as the homestay percentage above the pre-COVID normal (H%; or H-forcing), and the vaccinated percentage (Vc%; or V-forcing) impact the net reproductive rate (R0) of COVID-19 in ten island nations as a prototype, and then, extending it to 124 countries worldwide. Our H- and V-forcing model of R0 can explain the new trends in 106 countries. The disease transmission can be controlled by forcing down R0(H,Vc)<1 with an enforcement of continuous H>40% in 93% of countries with 0% vaccinated plus recovered, Vp. The required critical H% decreases with increasing Vp%, dropping it down to 20% with 25%Vp, and further down to 8% with 50%Vp. However, the regulations on H% are context-dependent and country-specific. Our model gives insights into forecasting and controlling the disease’s transmission behaviour when the effectiveness of the vaccines is a concern due to new variants, and/or there are delays in vaccination rollout programs.

Fuente: Scientific Reports