The NHS was well-versed in planning for winter, Ms Roberts said, but there had been “unprecedented demand” this year.
The flu vaccination was the best defence against the virus, she said.
“We know that the virus can be life-threatening or life -limiting for some of the most vulnerable in our population.” she explained.
“It’s really, really important that the public, where they can, get that flu vaccine.”
She also told BBC News that planned doctor’s strikes would put extra pressure on healthcare services.
“Our focus will continue to be on maintaining patient safety and delivering really high quality care to those who need us.
“We have quite a lot of preparation and planning to ensure we can maintain emergency care first and foremost, and support the best possible flow through our hospitals and healthcare system.”
Some elective appointments may need to be cancelled, she said, but patients were urged to attend as normal unless advised otherwise.