The Sinn Fein president has said Brexiteers must accept that new trading borders between Great Britain and the island of Ireland are a permanent consequence of the UK's exit from the EU.
Mary Lou McDonald said the focus now needs to be on resolving "some teething problems and difficulties" with new Irish Sea trading arrangements, not ditching the Northern Ireland Protocol that now governs the movement of goods.
"Brexit is for keeps, I mean this is a big game changer for all of us and it has to be managed in a way that is sensible, in a way that is fair," she told Sky News’ Sophy Ridge On Sunday.
She added: "None of us wanted trading barriers between our island and the island to Britain, or across the continent, but Brexit has happened and in some respects those that advocated it so strongly now need to very much accept the fact that these are the consequences of their decisions.
"For us on the island of Ireland, there is the immediate need to have the protocol work to protect Irish jobs and livelihoods, to secure the infrastructure of our peace process."
Sinn Fein leader Mary Lou McDonald says there are "some teething problems and difficulties" with the Northern Ireland protocol and calls for the flexibilities in the protocol to be used to "iron out and mitigate those initial problems" #Ridge— Sophy Ridge on Sunday (@RidgeOnSunday) February 7, 2021
Latest: https://t.co/MHVln75FBC pic.twitter.com/7PEVDeAytw
Ms McDonald said there are "some teething problems and difficulties" with the Northern Ireland protocol.
She called for the flexibilities in the protocol should be used to "iron out and mitigate those initial problems".
"Brexit was never a good idea, we argued strongly against it," Ms McDonald said, adding that it "should not come as a surprise to any sensible person" that there have been difficulties.
Ms McDonald said she believed such difficulties are "surmountable".
The Sinn Fein leader also acknowledged that the EU's threat to invoke Article 16 of the protocol with regards to Covid vaccine supplies was "absolutely ill judged and fortunately the European institutions stepped back from that very quickly".
Sinn Fein leader Mary Lou McDonald acknowledges that the EU's threat to invoke Article 16 of the protocol with regards to vaccine supplies was "absolutely ill judged and fortunately the European institutions stepped back from that very quickly" #Ridge https://t.co/MHVln75FBC pic.twitter.com/Gzc1QnK0Ar— Sophy Ridge on Sunday (@RidgeOnSunday) February 7, 2021
Meanwhile Ms McDonald urged the UK to share any excess coronavirus vaccinations with Ireland.
Asked if she would like to see spare doses being diverted to the Irish Republic, given the slower pace of rollout in the EU.
"Certainly if there is an excess of supply in Britain and if there is a capacity for that to be shared with Ireland at some point, well yes of course, absolutely, the project here is to get people vaccinated," she said.
"This is a race against this virus and against death so yes I think a spirit of fairness and generosity needs to prevail in this, my goodness, above all other issues, so yes is the answer and if the scenario were vice versa I would expect that a similar generosity would be afforded to the British people because the virus doesn't care about politics or borders or any of these things.
"We all share the same human biology and it's just so important that the incredible work that has been done by scientists internationally, including at Oxford University, and across the globe that the fruits of that endeavour and knowledge and expertise is shared in the way that good science would intend and that means keeping all of our fellow human citizens safe and alive and well."
Mrs McDonald said she would like to see a spirit of "generosity and solidarity" on vaccine sharing extend globally, and not just between the UK and Ireland.