European lockdowns and the consequences of relaxation during the COVID-19 pandemic

Glass, D. H.

This paper investigates the lockdowns introduced in France, Germany, Italy, Spain and the UK using data on the daily number of confirmed cases, deaths and, in the case of the UK, hospital numbers. The analysis employs a two-stage SEIR model with different reproductive numbers pre- and post-lockdown, which have been estimated from the data for each country. The model is evaluated by considering its predictive accuracy on current data and it is then deployed to explore the potential consequences of partial relaxations of the lockdowns. The results suggest that there is a substantial difference between relaxations of 25% and 50% with respect to the pre-lockdown situation. The latter could lead to second peaks that are higher than the earlier peaks in all of the countries. The former would likely be very serious in the UK, would halt the decline in numbers in most countries and could lead to second peaks in some countries. Calculations also suggest that a relaxation of no more than about 10-15% would be needed if cases of COVID-19 are to continue to decline in all five countries.