China’s health commission said a combination of pathogens is causing a surge in acute respiratory infections across the country, reiterating previous comments aimed at easing concerns a novel virus may be the source.

Influenza is one of the main causes of the spike in cases, National Health Commission spokesman Mi Feng said at a press conference on Sunday. Rhinovirus, mycoplasma pneumoniae and respiratory syncytial virus are also circulating, he said. The country should guarantee medicine supply and open more areas for medical treatment, Feng said.

Outbreaks of respiratory diseases have been hitting kids particularly hard and seen anxious parents sometimes wait for hours for their children to see a doctor. The Chinese Center for Disease Control and Prevention and Beijing Children’s Hospital told the World Health Organization on Thursday that there have been increases in outpatient visits and hospitalizations, but so far the sources of the illnesses are all known germs.

The details came after WHO requested more information from China on the situation following a report about undiagnosed pneumonia in children’s hospitals in Beijing, Liaoning and other places. The group has said that while the level of illness is high for this time of year, it’s not unusual for winter to bring respiratory diseases. They advised people to take basic precautions to reduce their risk, and said there’s no need for any travel restrictions based on the current situation.

Doctors have been warning for weeks about a likely spike in “walking pneumonia” cases and local Chinese media have reported a steady rise in infections from mycoplasma among kindergarten and primary school children. While the germ tends to cause only mild colds in older kids and adults with robust immune systems, younger children are prone to develop pneumonia – with symptoms lasting for weeks.