DUP leader Sir Jeffrey Donaldson has tested positive for Covid-19.
The Lagan Valley MP said close contacts will be informed and he will continue with his work remotely.
Sir Jeffrey added that the "importance of being vaccinated cannot be overstated".
In a series of tweets he said: "When I returned from London on Friday evening I felt a cold coming on but it has been getting worse.
"PCR test has now come back positive. Close contacts will be notified. Thankfully I received my booster two weeks ago.
"The importance of being vaccinated cannot be overstated."
Sir Jeffrey said he would still hold a virtual meeting with Foreign Secretary Liz Truss, who recently replaced Lord Frost as the UK's lead negotiator with the EU in post-Brexit talks.
The DUP leader tweeted: "Work still goes on even though I'm a bit croaky. Sore throat is most uncomfortable symptom.
"I will still be having a virtual meeting with the Foreign Secretary Liz Truss this afternoon on the need to remove the Irish Sea border which is reducing accessibility to medicines etc."
Share your views on the Omicron variant below, or click here.
