Several respiratory viruses are circulating in China right now, but seasonal influenza is the dominant one. Surveillance data show influenza A(H3N2) accounts for the vast majority of confirmed flu cases, alongside smaller waves of respiratory syncytial virus (RSV), human metapneumovirus (hMPV), COVID-19, and a bacterial infection called Mycoplasma pneumoniae that is hitting children especially hard.
Influenza A(H3N2) Is the Main Culprit
Influenza is the most commonly detected respiratory pathogen across all age groups in China. Of the influenza samples that tested positive in early 2025, 97.4% were influenza A, and nearly all of those were the H3N2 subtype. Influenza B made up just 2.6% of positive results. Dozens of flu outbreaks have been reported nationwide, with the overwhelming majority linked to H3N2.
H3N2 is not a new or unusual strain. It circulates globally every winter season. But it tends to cause more severe illness than some other flu subtypes, particularly in older adults. The pattern in China mirrors what other Northern Hemisphere countries typically see during peak flu season.
Mycoplasma Pneumoniae in Children
For children between the ages of 5 and 14, the most commonly detected respiratory pathogen is not a virus at all. It is Mycoplasma pneumoniae, a type of bacteria that causes “walking pneumonia,” a lung infection that often feels like a lingering chest cold with a dry cough, fatigue, and sometimes fever. Most cases are mild enough that kids stay on their feet, but it can progress to a more serious pneumonia in some children.
What makes Mycoplasma pneumoniae particularly concerning in China is antibiotic resistance. The standard first-line antibiotics for this infection (a class called macrolides, which includes azithromycin) fail to work in roughly 80% of Chinese cases. That is far higher than in most other countries: resistance runs under 10% in the United States, about 12% in Canada, and averages around 5% across Europe. In practical terms, this means children in China who develop Mycoplasma pneumonia may need alternative antibiotics that carry more side effects.
Globally, 2024 saw an unusual rise in Mycoplasma infections among very young children, including toddlers and infants, age groups that historically were less affected. That shift was observed in the U.S. and elsewhere, and a similar pattern has played out in China.
COVID-19 Is Still Circulating
SARS-CoV-2 has not disappeared from the mix. The predominant COVID variant in China is called XDV (along with its sublineages), which accounted for 59.1% of sequenced samples as of late 2024. Globally, the WHO is also monitoring several other variants including KP.3.1.1 and newer lineages, though none have triggered the kind of alarm that earlier variants like Delta or Omicron did.
COVID continues to contribute to the overall respiratory illness burden, but it is no longer the leading driver of hospitalizations the way it was during earlier pandemic waves. For most people with up-to-date immunity from prior infection or vaccination, current variants tend to cause milder illness.
RSV and Human Metapneumovirus
Both RSV and hMPV are on the rise in China as part of the normal winter respiratory season. These viruses cause symptoms similar to a bad cold, including cough, congestion, wheezing, and fever. They are most dangerous for infants, very young children, and older adults with underlying health conditions. Neither virus is new or unexpected during winter months, but their combined circulation alongside flu and COVID adds strain to hospitals.
hMPV drew international attention in early 2025 when reports of rising cases in China made headlines, but the WHO confirmed that the increase was consistent with typical seasonal patterns seen across the Northern Hemisphere. There is no evidence of a novel or unusually dangerous pathogen emerging.
Sporadic Avian Flu Cases
China also reported four human cases of avian influenza A(H9N2) between December 2024 and January 2025. The cases involved a 72-year-old woman in Sichuan, a 2-year-old boy in Hunan, a 15-year-old boy in Hunan, and a 56-year-old woman in Guangdong. All four had direct exposure to live poultry, either backyard chickens or live poultry markets. None of the cases were linked to each other, and no family clusters developed, which means there is no sign of person-to-person spread.
No human cases of the more dangerous H5N1 bird flu strain were reported from China during this same period. H9N2 generally causes milder illness than H5N1, though it is closely monitored because avian flu viruses have the theoretical potential to adapt to human transmission.
How to Lower Your Risk
Flu vaccination remains the single most effective measure against the dominant circulating threat. Research shows that flu vaccination reduces healthy children’s risk of dying from influenza by nearly 65% and provides about 53% overall protection against flu-related hospitalization in kids. Priority groups for vaccination include older adults, people with chronic health conditions, healthcare workers, and children.
Beyond vaccination, the basics still apply: wash your hands frequently, avoid touching your face, stay home when you are sick, and wear a mask in crowded indoor spaces during peak respiratory season. Good ventilation helps too. Opening windows to cycle fresh air through a room reduces the concentration of airborne virus particles more effectively than most people realize.
If you develop flu-like symptoms, rest and hydration are the first steps. Mild cases can typically be managed at home. Symptoms that should prompt medical attention include difficulty breathing, chest pain, persistent high fever, or symptoms that improve and then suddenly worsen, which can signal a secondary bacterial infection.