The World Health Organization is investigating mysterious cases of pneumonia among Chinese children. Here’s what you need to know

Officials from China’s National Health Commission reported an increase in respiratory illness at a Nov. 13 press conference, the WHO said in a Wednesday press release. Chinese officials at the time attributed the increase to the lifting of COVID-19 restrictions, which occurred a year ago, and the circulation of viruses like flu and RSV.

On Tuesday additional reports were received of undiagnosed pneumonia in children in northern China. It was unclear if the cases overlapped with those reported by Chinese officials earlier in the month, the WHO stated.

On Wednesday the WHO requested additional information including patient lab results, as well as information about the circulation of known respiratory pathogens like flu, COVID-19, and RSV, and how such circulation is affecting health care systems, the organization said.

Northern China has reported an increase in flu-like illness over the past month, when compared to levels seen during the past three years, according to the WHO.

While the WHO seeks additional information, it recommends that Chinese citizens obtain recommended vaccinations, maintain distance from those who are ill, stay home when sick, wear masks “as appropriate,” ensure good ventilation, wash their hands, and obtain medical care as needed.

This is a developing story and will be updated.