SEDRA: Selective Entry Dynamic Risk Assessment: A mathematical model to safely keep the borders open during Covid-19

1. The Covid-19 pandemic has brought the World to a near standstill for most of 2020 and 2021, causing chaos in international travel, driving many economies into the ground, particularly those largely based on tourism. The lack of standard tools to assist decision makers in structuring a coherent policy to allow foreign passengers into their county and the resulting panic-mode opening/closing the borders on every “new case” outburst or new variant “of concern”, have led several countries to costly and often meaningless decisions based on fear rather than science or logic. This study aims at providing a universal method to safely keep the borders open and allow conditional immigration to foreign passengers according to a “Risk Group” table that includes all the countries reporting data on their Covid-19 situation to the WHO and other organisms. The RG table is recalculated on a weekly basis according to a mathematical model described in this paper, dynamically assessing the status of the pandemic worldwide through the calculation of a “Safety Index” for each country. A prototype algorithm has been implemented in VBA/EXCEL and its results are published bi-weekly on a Github repository.