China Experiences Significant Surge in Influenza Activity, H3N2 Strain Dominant

Influenza Activity Reaches High Levels Across China

China is currently experiencing a significant surge in influenza activity, with recent data indicating that 51.1 percent of outpatient visits for influenza-like illnesses (ILI) tested positive for the flu during the week starting November 24. This marks an increase from 44.8 percent in the preceding week, according to the Chinese Center for Disease Control and Prevention (China CDC).

The heightened flu season has led to high activity levels in 17 provinces across the country, while other regions report moderate spread. The current flu season commenced earlier than usual, with Beijing observing its onset around mid-November, approximately four weeks earlier than the previous season. Experts anticipate that influenza activity is likely to peak in early to mid-December.

Dominant Strains and Affected Demographics

The predominant strain circulating is Influenza A (H3N2), which accounts for over 95 percent of infections in some areas. While H3N2 is the primary concern, a smaller proportion of cases involve the H1N1 strain of Influenza A and Influenza B viruses. This year's flu season follows a period of minimal influenza activity during the COVID-19 pandemic, which may have contributed to lower population immunity to circulating strains.

A notable demographic affected by the surge is children aged 5 to 14 years, who show a markedly higher flu positivity rate compared to other age groups. This has resulted in an increased number of flu infection clusters, particularly within educational settings such as schools.

Public Health Response and International Monitoring

In response to the escalating situation, China's National Health Commission (NHC) and the China CDC have issued recommendations for enhanced public health measures. These include:

• Strengthening health monitoring in key facilities like nurseries, schools, and elderly care homes.
• Prompt detection and management of infection clusters.
• Advising the public to adopt personal protective measures.
• Instructing local authorities to expand medical service supply.

The World Health Organization (WHO) has been monitoring the situation, receiving data from Chinese health officials. The WHO has indicated that the current epidemiological situation in China reflects a seasonal rise in respiratory infections caused by common pathogens and does not present an unusual concern for the EU/EEA. Chinese authorities have also maintained that the country's hospitals are not currently overloaded.

Outlook

While influenza is the most commonly detected respiratory pathogen, other viruses such as respiratory syncytial virus (RSV), rhinovirus, and human metapneumovirus (HMPV) are also circulating. However, flu maintains the highest positivity rate among monitored pathogens for most age groups. Health officials emphasize the importance of continued vigilance and adherence to preventive measures as the flu season progresses.