When this article was originally published in Epidemiology & Infection, the funding statement was inaccurate. This has been updated in the article to the following:
The project is co-financed by the European Regional Development Fund of the European Union and Greek national funds through 1. the Operational Program Competitiveness, Entrepreneurship and Innovation (EPAnEK), NSRF 2014-2020 (Project code MIS: OΠΣ 5047228), and 2. the Operational Programme Epirus 2014–2020 of the Prefecture of Epirus (Project code MIS: HΠ1AB-0028180).