Naomi Long will not attend today's Alliance Party Conference after being diagnosed with a severe chest infection, the party has announced.
Mrs Long, who had been due to deliver the keynote address at the party's conference at the Stormont Hotel today, has been instructed to remain housebound under doctor's orders.
Stephen Farry MP will deliver the address in her absence.
Mrs Long tweeted: "Totally gutted to be missing our biggest ever Party Conference today.
"Unfortunately, I've been diagnosed with a severe respiratory infection and am on bed rest and fluids under doctor's orders.
"Sending best wishes to everyone: have a brilliant day!"
She added: "Also want to say an enormous thank you tol all the staff at Ulster Hospital for taking such good care of me yesterday.
"The pressure under which they were working in ED was unbelievable for a Friday afternoon but they were amazing.
"We are so lucky to have the NHS."