It said China has systems in place to capture information on disease incidence trends and report that data to platforms such as the Global Influenza Surveillance and Response System.
In recent days, media in cities such as Xian in the northwest have posted videos of hospitals crowded with parents and children waiting for tests.
Some social media users have posted photos of children doing homework while receiving intravenous drips in the hospital.
WHO said that while it was seeking additional information, it recommended that people in China follow measures to reduce the risk of respiratory disease.
It said such measures include vaccination, maintaining distance from sick people, staying home when sick, getting testing and medical care as needed, wearing masks appropriately, ensuring good ventilation and washing hands regularly.