At this stage, there is nothing to suggest that it may be a new variant of COVID," he said.
"One thing to note is that we can be reassured that the surveillance processes are working, which is a very good thing."
Parents in Shanghai on Friday said they were not overly concerned about the wave of sickness, saying while it appeared to be more severe, they expected it to blow over soon.
"Colds happen all over the world," said Emily Wu outside a children's hospital. "I hope that people will not be biased because of the pandemic ... but look at this from a scientific perspective."
Another mother, Feng Zixun, said she was making her eight-year-old son wear a mask and wash his hands more often but nothing much more.
"It's not that bad, there are more children falling sick now but it's mainly an issue of protection," she said.
Reporting by Andrew Silver and Nicoco Chan in Shanghai and the Beijing Newsroom; writing by Brenda Goh; Editing by Robert Birsel