The World Health Organization recently released a report stating that the current situation of influenza virus transmission in many countries around the world is severe. From January 10th to 16th, the number of people seeking medical treatment for respiratory symptoms in most reporting countries has generally increased, and the number of hospitalizations remains high. On January 10th, the Pan American Health Organization issued an epidemiological warning stating that the positive rate of influenza in the Americas continues to rise. At the same time, there has been a significant increase in hospitalized cases of influenza in many European and Asian countries, with hospitalization data in countries such as the UK and Japan reaching a new high for the same period in previous years. The World Health Organization calls on countries to prioritize vaccination of key populations as a core prevention and control measure, and strengthen multidimensional response measures. Since October last year, the intensity of influenza activity has continued to rise. The World Health Organization's "Global Situation of Seasonal Influenza" report released at the end of last year pointed out that since October 2025, the intensity of global influenza activity has continued to rise. The northern hemisphere epidemic has shown the characteristics of "early arrival, fast spread, and high intensity", while some countries in the southern hemisphere have continued to have a long-term epidemic trend. The K sub branch of influenza A H3N2 virus (hereinafter referred to as "K sub branch") is the current dominant strain. Since its discovery in Oceania in August last year, it has spread to more than 30 countries and regions worldwide, accounting for over 90% of the prevalent strains in Europe, America, and East Asia, forming a global cross regional epidemic trend. According to data from the European region of the World Health Organization, influenza activity levels in many European countries are at high or extremely high levels. In countries such as Ireland, the United Kingdom, and Serbia, more than half of flu like patients test positive, with 90% of confirmed cases being K-sub branch infections. According to data from the UK National Health Service, in the second week of January, English hospitals admitted 3140 cases of influenza, an increase of 18% compared to the previous week, setting a new high for the same period in previous years. The hospital bed occupancy rate continued to exceed 90%, maintaining a "high alert" state. On January 12th, several hospital trusts in the UK announced a "critical incident" status to cope with the continued pressure on medical treatment services. Declaring a 'critical incident' means that the hospital cannot take additional measures to protect patients and can only prioritize taking care of the most severely ill patients. Ted Van Essen, Chairman of the Dutch Immunization Foundation, has warned that the K-sub branch of the pandemic in the UK may quickly spread to the Netherlands. If the infection scale approaches the level of 2018, the number of hospitalizations in the Netherlands may reach 90000, putting significant pressure on the healthcare system. The latest data from the Centers for Disease Control and Prevention in the United States shows that as of January 16th, the cumulative number of influenza cases in the United States this season has exceeded 18 million, with 230000 hospitalizations and 9300 deaths. More than 90% of the prevalent strains are the K sub branch. The Centers for Disease Control and Prevention (CDC) in the United States has stated that influenza is still prevalent, but the virus transmission has been decreasing or stabilizing for two consecutive weeks and will continue to be monitored to prevent a new wave of influenza activity. In the Asian region, monitoring by the Japanese Ministry of Health, Labour and Welfare shows that the K-sub branch accounts for 96% of the influenza epidemic strains in Japan. Since December last year, the weekly number of new cases has exceeded 190000, and many places have issued influenza alerts. The scope of school closures continues to expand. Associate Professor Kazuo Kitari from Nagasaki University in Japan bluntly stated that both the burden on the healthcare system and drug reserves are facing severe challenges. South Korea has raised its influenza alert level to 'high'. Experts warn that if the epidemic continues, it may experience the most severe flu season since 2016. On January 8th, the Indonesian health department reported that 63 confirmed cases of influenza A H3N2 (all from the K sub branch) have been detected domestically. The overall situation of the epidemic is currently under control, and the community transmission situation is being closely monitored. Vaccination remains the most effective means of preventing influenza. Virological studies have shown that the core feature of the K subfamily is the occurrence of key mutations such as T135K and K189R in the virus surface hemagglutinin protein. The efficiency of adhering to human respiratory cells has significantly increased compared to previous epidemic strains, which is one of the main reasons for its fast transmission rate and high incidence of clustered infections. In addition, the H3N2 subtype of A has not been widely prevalent in the past two years, and the population generally lacks targeted immune barriers, further promoting the spread of the epidemic. According to the monitoring of the Global Alliance for Vaccines and Immunization, although the influenza virus continues to evolve, the evolutionary path of the K sub branch is normal and no breakthrough mutations have occurred. Nicola Lewis, Director of the World Influenza Center at the Francis Crick Institute in the UK, believes that "super flu" is not a scientific term. Existing evidence suggests that the K sub branch is essentially a variant of the influenza A H3N2 virus, with no more severe illness than other influenza subtypes. Symptoms are consistent with regular flu, mainly characterized by high fever, muscle soreness, and respiratory symptoms. The severity of the condition mainly depends on the immune system, basic health status, and timely treatment of the infected person. Regarding the spread of influenza, the World Health Organization emphasizes that vaccination remains the most effective means of preventing influenza. The WHO Vaccine Development Advisory Group pointed out that existing cell culture vaccines have a high overall compatibility with the K sub branch and excellent protective effects. According to monitoring by the Pan American Health Organization and the World Health Organization, the protective efficacy of vaccines for severe illness and hospitalization in children during this influenza season is about 75%, and for adults it is about 30% to 40%, significantly reducing the risk of severe illness and death. The Director of the WHO Regional Office for Europe, Kluge, stated that the early arrival of the 2025-2026 flu season has caused some populations to miss the optimal vaccination window, such as Swiss people who are accustomed to getting vaccinated from the end of December to early January, resulting in the establishment of immune barriers lagging behind virus transmission. At the same time, some members of the public have misconceptions and confuse influenza with the common cold, engaging in behaviors such as "rushing to reduce fever" and "blindly using anti-inflammatory drugs". The clinical guidelines of the World Health Organization explicitly remind that antibiotics such as amoxicillin and cephalosporin are ineffective against viral infections, and blind use may delay treatment or trigger drug resistance. Countries need to strengthen the sharing of virus monitoring data, mutual learning of prevention and control experience, and mutual assistance in medical resources. The World Health Organization stated that countries need to accelerate the promotion of vaccination, especially to cover high-risk populations. Currently, the lack of vaccine accessibility and limited medical resources in developing countries have further exacerbated the imbalance in global prevention and control. In early January, the World Health Organization, in collaboration with the Global Alliance for Vaccines and Immunization, donated the first batch of 4 million doses of influenza vaccine to 12 low-income countries in Southeast Asia and Africa, with a focus on areas with rapidly rising outbreaks such as Indonesia and Ethiopia. At the same time, vaccine manufacturers have accelerated the release of production capacity and signed supplementary supply agreements with multiple Latin American countries to ensure vaccine supply for countries in the southern hemisphere during the extended flu season. Various countries have simultaneously strengthened prevention and control measures and health education, and new progress has been made in the research and application of influenza treatment drugs. The World Health Organization recommends that the public maintain good hygiene habits, cover their mouth and nose when coughing or sneezing, wash their hands frequently, avoid contact with influenza patients, wear masks scientifically after symptoms appear, reduce visits to crowded places, and proactively disclose contact history when seeking medical attention. At the same time, key populations can receive pneumococcal vaccines simultaneously to enhance their comprehensive protection capabilities. In May 2025, the 78th World Health Assembly passed the "World Health Organization Pandemic Agreement", providing mechanism guarantees for the global response to infectious diseases such as influenza, and clarifying core principles such as fair access to public health products such as vaccines and therapies, and the construction of global supply chains. Zhang Wenqing, the head of the World Health Organization's global influenza program, called on all parties to plan emergency resources in advance, strengthen protection for vulnerable groups, enhance the health system's reception and referral capabilities, and be alert to the transmission risks brought by personnel movements during the holiday season. The World Health Organization emphasizes that influenza prevention and control knows no borders. Countries need to strengthen the sharing of virus monitoring data, mutual learning of prevention and control experience, and mutual assistance in medical resources, with a focus on the prevention and control needs of developing countries. Through comprehensive and coordinated response, the impact of influenza on global public health and economic society can be minimized to the greatest extent possible. (New Society)