The WHO requested information following reports of undiagnosed pneumonia in children. China’s response included epidemiologic, clinical, and laboratory data. Known pathogens like mycoplasma pneumoniae, influenza, RSV, and adenovirus are implicated. The WHO continues to monitor the situation and has requested additional information on pathogen trends and healthcare impacts. Beijing faces a high incidence of respiratory diseases with multiple pathogens, including mycoplasma pneumonia.