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Night curfew may have increased the spread of COVID-19 in Greece

During the pandemic, many countries have imposed night curfews in an attempt to reduce the spread of COVID-19.

How successful have these measures been? According to a recent study, they may have actually increased transmission.

Sotiris Georganas and colleagues took advantage of a natural experiment in Greece whereby the timing of night curfew shifted in one region but not in another. While a 9pm curfew had been in place throughout the country since November of 2020, a 6pm weekend curfew was introduced on 6th February in the Attica region (which includes Athens).

The authors used Google mobility data to examine how time spent at home, and time spent at groceries/pharmacies, changed in the Attica region and the Epirus and Western Macedonia region (where the timing of night curfew did not shift).

Specifically, they examined mobility data in each region in the five weekends before the shift, as well as the four weekends after.

What did the authors find? Compared to the Epirus & Western Macedonia region, the Attica region saw a small and statistically significant increase in time spent at home, as well as a small and non-significant decrease in time spent at groceries/pharmacies. In other words, the shift in the timing of night curfew had – at best – a marginal impact on mobility.

Given that the shift reduced the time available for shopping by three full hours (a change of almost 20%), the overall effect will have been to increase crowding – by concentrating roughly the same amount of shopping into a shorter time period. As a consequence, it may well have led to a rise in transmission.

In the authors’ words,

“As more people were present simultaneously in high-risk places such as supermarkets, the early curfew backfired.”

This finding suggests that governments should focus on protecting care homes and hospitals, rather than trying to control the epidemic by tweaking people’s shopping habits.