Sinn Féin's Michelle O'Neill is self-isolating after a family member tested positive for COVID-19.
Northern Ireland's Deputy First Minister is now awaiting a test for the virus.
A spokesperson for the party has said Ms O'Neill will continue to carry out her Stormont duties remotely.
Party leader Mary Lou McDonald also confirmed the deputy leader's diagnosis.
She said: "Michelle will be self-isolating and following all of the good public health advice, as she has been a close contact of someone who has tested positive.
"We wish her well, and her family member well."
Deputy McDonald noted she had contracted the virus herself, and "would not wish it on anybody"
Sinn Féin TD Louise O'Neill, meanwhile, told The Pat Kenny Show there shouldn't be any stigma around getting a coronavirus test.
She said: "We need to be more open and transparent - it's going to become more and more part of people's lives.
"I want to take this opportunity to wish Michelle and her family well."