Waiting times to see doctors stretch for hours, with hundreds of patients lining up at some children's hospitals in major cities across northern China, according to state media, Chinese social media platforms and CNN.
The world is concerned about the health situation in China, as the central city of Wuhan was the birthplace of the Corona virus in late 2019, and the devastating repercussions it caused on the health and economic situation for years worldwide.
On Tuesday, an official at the Beijing Children's Hospital told state media that the current average of more than 7,<> patients a day "far exceeds the hospital's capacity."
In the neighboring city of Tianjin, the largest children's hospital broke a record on Saturday, admitting more than 13,<> children in outpatient and emergency departments, according to a local state-run outlet.
When CNN called to inquire about booking appointments at Beijing's Friendship Hospital on Thursday, the employee said it could take a full day to see a pediatrician.
Health officials in Beijing and other major cities in northern China said seasonal illnesses, including influenza and respiratory syncytial virus (RSV), as well as mycoplasma, a bacterial infection that is usually mild and affects children, were the reasons behind overcrowded hospitals.
The rise in cases across northern China coincides with an increase in seasonal respiratory infections in the northern hemisphere, including the United States, where respiratory syncytial virus is spreading at "unprecedented" levels among children.
But the situation in China has sparked global concern after the World Health Organization asked the country on Wednesday for more information about the rise in respiratory diseases and "undiagnosed pneumonia in children."
However, after speaking with health and hospital officials in China on Thursday, the WHO said the data indicated an increase in outpatient consultations and pediatric hospitalizations due to pneumonia (mycoplasma) in May, common seasonal diseases, adenovirus and influenza virus, since last October.
"Some of these increases occurred earlier in the season than historically, but are expected due to the lifting of coronavirus restrictions, as has similarly happened in other countries," the WHO said.
The WHO added that Chinese authorities had not detected any unusual or new pathogens or unusual clinical symptoms.
Experts monitoring the situation noted that there was no evidence of a new pathogen emerged, but called on China to share more information about the health situation with the public.
Jin Dongyan, a virologist at the University of Hong Kong's School of Biomedical Sciences, told CNN: "We don't think there's an unknown nurse hiding somewhere. There is no evidence of that."
But Catherine Bennett, an epidemiologist at Deakin University in Australia, said the main concern was whether the rise in cases of pneumonia in children was indicative of a new pathogen or new levels of disease severity.
"So far we have not heard reports of either of them," she said, adding that "it is important to monitor sources of infection to rule out such concerns."