Disease modeling in the midst of a pandemic

How simple mathematical models can help us get a better understanding of the current situation.

Disclaimer: I am not a medical doctor nor an epidemiologist. I’m just an applied mathematician. The sole aim of this new series is to provide a better understanding of (fairly simplified) epidemiological models to an audience as large as possible as well as illustrating some of the challenges a disease such as COVID-19 poses from a mathematical modeling point of view. Nothing more.

France entered its second lock-down nearly ten days ago. It will last at least until early December, quite possibly until the first days of 2021. These announcements occurred shortly before I gave my very last course on Mathematical modeling to a group of mechanical engineering students. After the class, some of them came to me and asked numerous questions about disease modeling and how mathematical models could be used to guide policymakers in these troubled times or to explain the scientific rationale behind the recent political decisions in a simple way to their relatives. Their questions mainly revolved around the following themes :

• What intuition could be gained from simple models?
• How are the parameters of these models estimated from real-life…