The Chief Medical Officers of the Republic of Ireland and Northern Ireland advised people in both jurisdictions to avoid all but necessary journeys across the border.
Acting Chief Medical Officer, Dr Ronan Glynn, and Chief Medical Officer for Northern Ireland, Dr Michael McBride, said that closer collaboration was needed between the Republic and the North.
The pair met in the wake of the news that Donegal is moving to level three of the Irish Government's 'Living with Covid' plan.
In a joint statement this afternoon, the CMOs said: “Given the current number of new cases in Donegal and neighbouring areas of NI in Derry, Strabane and Fermanagh we would appeal to everyone to avoid all but necessary travel across the border.
Dr Glynn and Dr McBride also recommended that employers on both sides of the border make every effort to facilitate employees to working from home.
They said: "We realise that for those living in border areas this will not be welcome news but we must prevent further spread of this virus and we can only do so by working together to protect each other.”
During the meeting, the pair discussed the growing prevalence of the virus in both the Republic and the North, and underlined the need for ongoing cooperation and collaboration.
They said their review was not solely focused on Donegal and Derry, but also on other areas along the border where the profile of the disease is continuing to evolve.
The Chief Medical Officers did, however, express concern at the proportion of confirmed Covid-19 cases amongst younger people in Donegal and Derry, and they called on them to limit their social contacts.
Dr Glynn and Dr McBride jointly appealed to the public across the island to continue to follow public health advice to keep themselves and others safe.