Deputy First Minister Michelle O'Neill said she contemplated going to hospital as she suffered a "quite severe" bout of Covid-19 in recent weeks.
Ms O'Neill announced on 31 August that she had contracted the virus.
She said she was "absolutely floored" and it was probably her "worst experience" of illness.
The Sinn Féin vice-president, who returned to Stormont on Monday, said she was "so grateful" she was fully vaccinated.
"Given that I felt so bad, I can only imagine what it would have been like if you didn't have the vaccination," she told BBC News NI.
Ms O'Neill said she would meet executive colleagues on Thursday and stressed it would be "dishonest" of ministers to rule out future restrictions ahead of what she described as a potentially "difficult winter".
She said she wanted to use her personal experience to encourage more people to get vaccinated.
Describing one evening during her illness, Ms O'Neill said she felt "frightened" and "scared" by her symptoms and "contemplated hospitalisation".
"I contemplated did I need to speak to my children," she continued, and explained that people know "how tragic" Covid-19 can be.
"I think I would have been hospitalised had it not been for the vaccination, so I would use this opportunity to say to people who still haven't taken that step to please get the vaccine, particularly that younger cohort of people," she said.
"This is a horrible, horrible illness. I don't want to see anyone experience it."
Despite being back at work, Ms O'Neill said she did not feel back to "100% capacity", but also did not have any concerns about suffering 'long Covid'.
She explained that she had not fully recovered her sense of smell nor taste, but was "well-improved".
"It's day and night in terms of where I was a couple of weeks ago, so I'm fit enough to be at work, I'm fit enough to be back at my desk and fit enough to carry out my duties, but hopefully no long-Covid to be seen."
Referencing comments by First Minister Paul Givan that he wanted all regulations in Northern Ireland to be lifted by the end of September, Ms O'Neill said "we're nowhere near the point where we can start to lift restrictions".
"I think it's unfortunate that some ministers have decided to say publicly and put dates to end points, that's not where we're at," she said.
"I certainly would want to avoid us getting back to the situation where we have to have circuit-breakers or lockdown, but the only way we will be successful in doing so is that if we take a preventative approach, that we take a cautious approach."