Breaks and Breakouts: Explaining the Persistence of COVID-19

This paper investigates the role of large-outbreaks on the persistence of Covid-19 over time. Using data from 649 European regions in 14 countries, I first show that school-breaks in late February/early March (weeks 8, 9 and 10) led to large regional outbreaks of Covid-19 in the spring with the spread being 60% and up-to over 90% higher compared to regions with earlier breaks. While the impact of these initial large-outbreaks fades away over the summer months it systematically reappears from the fall as regions with school-breaks in weeks 8, 9 and 10 had 30-70% higher spread. This suggests that following a large-outbreak there is a strong element of underlying (latent) regional persistence of Covid-19. The strong degree of persistence highlights the long-term benefits of effective (initial) containment policies as once a large outbreak has occurred, Covid-19 persists. This results emphasizes the need for vaccinations against Covid-19 in regions that have experienced large outbreaks, but are well below herd-immunity, to avoid a new wave of cases from the fall of 2021.