Hospitals across China are facing overwhelming pressure as the A(H3N2) influenza strain spreads at an alarming rate. The rapid rise in cases since late November 2024 has left medical facilities in Beijing and at least 17 provinces struggling to keep up.
In just a matter of days, antiviral medication purchases on Alibaba Health surged by 500%, while parents reported hours-long waits at children’s hospitals.
What’s more troubling? The outbreak has now spread beyond China’s borders. What’s driving this significant health crisis, and how is the world reacting?
Three-Nation Crisis
A(H3N2), dubbed “superflu” in the UK, now dominates in China, Russia, and England. Russia reported over 23,400 influenza cases, with just above 80% identified as A(H3N2)—a 20% surge in flu cases.
England’s UK Health Security Agency confirms A(H3N2) as the predominant strain circulating in the country.
The outbreak exposes hundreds of millions across the three nations to continued transmission. What’s driving this rapid spread?
H3N2’s Evolution
Influenza A(H3N2) has circulated since 1968, but the current subclade K has emerged recently with significant mutations.
In Jiaxing, China, surveillance data showed six epidemic peaks from 2019–2024, with the 2024 sequences shifting to clade 3C.2a1b.2a.2a.3a.1.
Following the relaxation of COVID-19 containment measures, influenza activity rebounded sharply in 2023–2024 across China. The genetic evolution of this strain presents challenges for vaccine formulation timing.
Mounting Pressures
China’s flu infection rate entered a period of rapid increase in late November 2024, according to Peng Zhibin of China’s Center for Disease Control and Prevention.
Low vaccination rates exacerbate surges—China’s influenza vaccination rate is comparatively lower than the global average.
Russia simultaneously reported a 13.7% rise in COVID-19 cases, reaching approximately 11,000 cases. Hospitals in Tianjin and Hebei strain under concurrent demand.
Superflu Revealed
A(H3N2) subclade K, referred to as “superflu” by UK media, triggered a 500% surge in antiviral medication purchases in China between November 10 and 21, 2024.
The outbreak has overwhelmed hospitals across 17 provinces with elevated flu transmission. The hardest-hit regions include Beijing, Tianjin, Hebei, Henan, Guangdong, Fujian, Shandong, and Shanxi.
Russia’s first confirmed case occurred in October 2024, with subsequent spread to the Far East, Siberia, and other regions. The rapid emergence reflects ongoing antigenic drift in the virus.
China Hospital Strain
Beijing children’s hospitals experienced significant overcrowding, with extended wait times reported by residents. Seventeen provinces across China report hospital strain from elevated pediatric flu cases.
Alibaba Health platform data indicate a significant rise in demand for antiviral medications.
China’s CDC notes the national rapid rise in infection rates. Strain concentrates in major urban centers with high population density.
Human Impact Emerges
Parents in Beijing describe extended queues at overwhelmed facilities seeking treatment. Dr. Giuseppe Aragona warns: “H3N2 changes regularly, so the version of the virus circulating this year may be different from previous years or from the one in the seasonal vaccine, which can make people more susceptible.”
Russia’s approximately 69 million unvaccinated residents face vulnerability amid 23,400 documented cases. Healthcare systems face mounting pressure.
Regulatory Tracking
Rospotrebnadzor identifies A(H3N2) as the only respiratory virus with an upward trajectory in Russia, while other pathogens remain stable or declining.
The UK Health Security Agency confirms A(H3N2) as the predominant circulating strain in England and recommends seasonal vaccination.
China’s CDC actively monitors emerging clades, including 3C.2a1b.2a.2a.3a.1. Surveillance intensifies across all three nations. No emergency declarations have been issued as of December 2024.
Vaccine Efficacy Considerations
A(H3N2) continues to evolve through mutations affecting the HA (hemagglutinin) gene epitopes. According to the Jiaxing study analysis, 2023–2024 seasonal vaccines retained protective efficacy in the 29–54% range against local strains, reflecting the inherent challenge of vaccine formulation timing relative to real-time viral drift.
Russia maintains a 53.2% national vaccination rate (78.3 million people vaccinated), yet the 20% surge in flu cases demonstrates that vaccination alone—particularly in populations with lower coverage—cannot prevent all transmission.
While current UK hospitalization rates (2,660 per day) represent the highest levels for early December,
this reflects a recovery from exceptionally low baseline immunity following three years of suppressed
seasonal flu circulation—not a deviation from typical peak winter patterns. The 2022–23 season peaked
at 5,441 hospitalizations, providing context for the current trajectory.
Dual Respiratory Burden
Russia is simultaneously facing a surge in flu cases and a 13.7% rise in COVID-19 cases, reaching approximately 11,000, a dual respiratory burden despite ongoing vaccination campaigns.
A(H3N2) comprises just above 80% of positive influenza samples, making it the sole climbing pathogen among monitored viruses.
The concurrent elevation of both influenza and COVID-19 strains intensifies the strain on Russia’s healthcare infrastructure.
Expert Observations
Peng Zhibin of China’s CDC identifies the current period as one of “rapid increase” in flu transmission, while noting that lower vaccination rates hinder control efforts.
Russian health officials acknowledge that 69 million unvaccinated residents remain vulnerable to infection.
International experts express concern about the rapid spread pattern and note the challenges posed by antigenic drift. Stakeholder focus remains on monitoring and mitigation.
Surveillance Response
Rospotrebnadzor actively monitors the progression of the outbreak across Russian regions, including the Urals, Northwest, Far East, and Siberia.
The UK Health Security Agency issues weekly surveillance reports, confirming the continued predominance of A(H3N2). Alibaba Health data provides real-time indicators of medication demand in China.
Dr. Aragona and other medical experts continue raising awareness about the importance of understanding viral evolution. Authorities maintain vigilant monitoring amid the evolving situation.
Mitigation Strategies
Seasonal vaccination efforts target protection against A(H3N2); the Jiaxing study indicates that 2023–2024 vaccines retain meaningful efficacy, ranging from 49% to 54%, against local strains.
Russia has vaccinated 53.2% of its population; public health messaging encourages the expansion of vaccination coverage among unvaccinated populations. Chinese provinces promote hygiene measures and respiratory protection.
Antiviral medication supplies have been mobilized to meet the 500% increase in demand. Efforts accelerate across affected regions.
Expert Analysis
Dr. Aragona cautions: “H3N2 changes regularly, so the version of the virus circulating this year may be different from previous years or from the one in the seasonal vaccine, which can make people more susceptible.”
The Jiaxing study confirms antigenic drift but demonstrates that vaccines retain functional protective efficacy. Rospotrebnadzor notes stability in other respiratory viruses, with A(H3N2) as the exception.
Epidemiological outlook suggests continued circulation through the winter months. Ongoing vigilance remains warranted.
Winter Outlook
Will A(H3N2) sustain elevated transmission through 2025? England’s current predominance suggests potential for continued waves in the Northern Hemisphere.
China’s large exposed population and Russia’s regions across multiple climatic zones may experience extended circulation. Annual vaccine reformulation occurs based on WHO recommendations developed months in advance.
Epidemiological outcomes will depend on transmission patterns, population immunity, and the evolution of the virus. Northern Hemisphere health authorities monitor closely.
Public Health Context
China’s comparatively lower influenza vaccination rate, relative to global averages, contributes to its sustained transmission potential.
Following the relaxation of COVID-19 containment measures, H3N2 positivity rates rebounded sharply, indicating a reduction in population immunity due to years of suppressed seasonal flu circulation.
Hospitalization rates appear alarming, partly due to reduced population immunity from three years
of suppressed seasonal flu circulation during COVID-19 containment measures. Children ages 5–14
have been disproportionately affected, having missed typical childhood flu exposures.
The baseline from 2023–24 was exceptionally low (approximately 402 hospitalized in the UK), making the current 2,660 daily figure a 55% increase from a historically low baseline rather than from typical winter
levels. This post-COVID immunity gap explains elevated hospitalization rates even with established
public health responses in place.
Governments face increasing calls for vaccination promotion. Peng Zhibin’s CDC pushes enhanced surveillance capabilities. Policy implementation and viral evolution remain in a state of tension.
International Spread Pattern
A(H3N2) clade 3C.2a1b.2a.2a.3a.1 has spread from China to Russia (with the first reported case in October) and the UK.
Phylogenetic analysis from the Jiaxing study shows sequence overlap between Chinese strains and those detected in the UK and France, indicating international circulation.
Travel and human movement facilitate continued cross-border transmission. International surveillance networks remain activated.
Healthcare System Impact
Hospitalization rates and healthcare facility strain have increased across affected regions. Overcrowding in multiple Chinese provinces echoes patterns from earlier pandemic responses.
Hospitals in major urban centers, particularly pediatric facilities, experience increased demand. The healthcare system’s capacity remains adequate but strained in high-impact areas. Preparedness and surge capacity planning continue.
Public Response
Social media reports from Beijing document extended wait times at medical facilities, reflecting the public’s awareness of the outbreak’s severity.
Younger, unvaccinated populations in Russia face a proportionally higher risk. The “superflu” designation in UK media has elevated public attention and concern.
Increased mask usage and vaccination-seeking behaviors reflect an adaptive public response. Generational differences in vaccination acceptance persist.
What This Signals
This A(H3N2) outbreak highlights the rapid evolution of viral drift and transmission in the post-COVID era. The 500% surge in antiviral demand and multi-national spread pattern demonstrate the importance of maintaining agile surveillance systems and vaccine development pipelines.
With mismatched vaccine timing and a strained healthcare infrastructure, the outbreak highlights gaps in preparedness.
Sustained vigilance and adaptive public health responses will be crucial throughout the upcoming winter season.
Sources:
H3N2 Outbreak in China: 95% Strain Dominance Across 17 Provinces.” Straits Times Asia, December 4, 2025.
“China Faces Huge Surge in H3N2 Flu Cases.” Macao News, December 7, 2025.
“UK Hospitals Facing ‘Worst Case Scenario’ From Super Flu.” Reuters Health, December 11, 2025.
“NHS Facing ‘Worst Case Scenario’ December Amid ‘Super Flu’ Surge.” Sky News, December 11, 2025.
“Russia is Facing a New Enemy Among Its Own Troops.” Dagens, November 29, 2025.
“Catastrophic Flu Outbreak Reportedly Cripples Russian Troops on Kherson Front.” United24media, November 24, 2025.