09/04/2020 Virus Biology and Immune Response

Impact of isolation measures on infection propagation

animação de transmissão exponencial de um vírus
Credit: The New York Times

In this study, the authors developed a mathematical model of the COVID-19 infection in Europe with two main goals:

(1) To provide estimates for the actual number of infected individuals, and

(2) To evaluate whether the isolation measures taken by the different countries have been effective in reducing the speed of propagation of the disease and the number of deaths caused by it.

The authors used the reported number of deaths in each of 11 European countries as the main input to their model. They then used existing estimates of mortality rates and of the time interval between infection and death to infer the total number of cases in each country. Furthermore, by allowing for the number of new cases to depend on a measure of how fast the disease was propagating, they were also able to infer how governmental interventions affected the propagation of the disease. The results suggest that estimated real numbers of cases are greater than reported, by more than a factor 10 in many cases. In Italy and Spain, 10-15% of the population is estimated to be infected. At the same time, the results suggest that governmental interventions have been effective in reducing the propagation of the disease, especially complete lockdown and school closures.

By simulating how the disease would have progressed in the absence of interventions, the authors estimate that many thousands of lives across Europe have been saved because of these interventions. For instance, between Italy and Spain alone (the two countries where model estimates are more reliable because the disease has progressed further) more than 50,000 deaths were estimated to have been averted until the end of March.

Contributing Scientist: Alfonso Renart

Translation: Catarina Saboga


Scientific paper

Estimating the number of infections and the impact of non- pharmaceutical interventions on COVID-19 in 11 European countries