Table 1.

Contact-tracing apps (CTAs) with interoperability and the countries where they can be used.

Country	App name	Countries or regions where apps can be used outside of their own country
Germany	Corona-Warn-App	Belgium, Croatia, Denmark, Estonia, Finland, Germany, Ireland, Italy, Latvia, Lithuania, Malta, the Netherlands, Norway, Poland, Slovenia, Spain, and Switzerland
Switzerland	SwissCovid	Switzerland, Liechtenstein, and Germany
Estonia	HOIA	Belgium, Croatia, Denmark, Estonia, Finland, Germany, Ireland, Italy, Latvia, Lithuania, Malta, the Netherlands, Norway, Poland, Slovenia, Spain, Switzerland, and Cyprus
Spain	Radar COVID	Belgium, Croatia, Denmark, Finland, Germany, Italy, Lithuania, Malta, the Netherlands, Norway, Poland, Slovenia, Ireland, and Latvia
Slovenia	#OstaniZdrav	Austria, Belgium, Croatia, Denmark, Finland, Germany, Ireland, Italy, Latvia, the Netherlands, Poland, and Spain
Croatia	Stop COVID-19	Other European countries
Fiji	careFIJI	New Zealand
Norway	Smittestopp	Denmark, Germany, Ireland, Spain, Latvia, Poland, Cyprus, Croatia, Austria, Finland, the Netherlands, and Belgium
Denmark	Smittestop	Germany, Italy, Ireland, Spain, and Latvia
Finland	Koronavilkku	Other European countries
Ireland	COVID Tracker	Northern Ireland and other European countries
Belgium	Coronalert BE	Germany, the Netherlands, Spain, Ireland, Italy, Denmark, Latvia, Croatia, Poland, and Cyprus
Austria	Stopp Corona	Other European countries
Latvia	Apturi Covid Latvia	Ireland, Italy, Germany, Spain, Denmark, Croatia, Poland, the Netherlands, Belgium, Finland, Austria, Norway, Slovenia, Cyprus, Malta, and Lithuania
Lithuania	Korona Stop LT	Austria, Belgium, Cyprus, Czech Republic, Denmark, Finland, Germany, Ireland, Italy, Latvia, Lithuania, Malta, the Netherlands, Norway, Poland, Slovenia, Spain, and Croatia
Malta	COVID Alert Malta	Other European countries