The Irish company behind Ireland's Covid-19 tracker app has launched a similar service in the US states of New York and New Jersey.
It comes weeks after NearForm launched its app in the neighbouring states of Delaware and Pennsylvania.
The technology is now being used in Ireland, Northern Ireland, Gibraltar and Scotland with development underway in Jersey, the largest of the Channel Islands.
The US service will allow for interoperability and exposure notifications across state lines that also have exposure notification apps and use the same Bluetooth technology.
CEO of NearForm, Cian Ó Maidín, said: "In using open source peer-reviewed technology, interoperable with Pennsylvania and Delaware, the States of New York and New Jersey will allow citizens to engage, protect each other and break transmission chains."
The Irish app is one of three European apps taking part in a wider European interoperability project.
