Deputy First Minister Michelle O'Neill has said she was "completely floored" after testing positive for Covid-19.
The Sinn Féin deputy leader said it was "scary experience" and she now knows first-hand the importance of being vaccinated.
Ms O'Neill on Monday will make a full return to her official duties three weeks after contracting the deadly virus.
She urged the public to take up the vaccine to protect themselves and ease pressures on the health service, adding: "We need to continue to fight this together."
Writing in The Irish News, Ms O'Neill said: "Three weeks ago I tested positive for Covid-19. It completely floored me.
"Thankfully, I had both vaccinations - something I am immensely grateful for.
"I had avoided developing Covid for 18 months, despite some of my family at home contracting it previously.
"It was a scary experience. I can't even imagine going through it without the protection afforded to me by being fully vaccinated."
Mr O'Neill said she was fortunate that, despite the effects of the virus, she was able to care for herself at home rather than being admitted to hospital.
She added: "I always thought the vaccine would be my best chance of getting through Covid-19 if I were to contract it.
"Now I know just how important it was for me, and my family. The benefits speak for themselves and it is not lost on me just how lucky I was."
Ms O'Neill said there is an "uncertain trajectory" for the months ahead and warned the Stormont Executive must be prepared to reintroduce restrictions if necessary.
She said: "Our approach, first and foremost, should be preventative. We all need to make every effort to ensure we don't have to bring in the toughest of restrictions again.
"None of us want lockdowns or circuit breakers. We have to work to try avoid that. However, I do agree with Alan Stout from the BMA that we must be honest with the public in that we have to be prepared to do what is necessary at any given point."
Ms O'Neill added: "Unfortunately there are many people who haven't taken up the vaccine, including significant numbers in the 18-39 age group.
"The truth is that even those who are prepared to take their chances with Covid-19 will feel the impact if it is necessary to implement more restrictions. So if you haven't got around to getting the vaccine, now is the time.
"We all hoped we would be on more certain footing by now. But pandemics, as we have learned, are unpredictable.
"We need to continue to fight this together."
