Core Insights - The overall trend of acute respiratory infectious diseases in China is on the rise, with influenza viruses being the primary pathogens, and a peak in influenza cases is expected around mid-December [1][4][5] Summary by Categories Current Situation - 17 provinces in China have reached a high level of influenza activity, while other provinces are at a moderate level [5] - The influenza activity level is not expected to decline to low levels for some time, indicating that influenza prevention and control measures should remain in place for the next 6-8 weeks [5] Influenza Statistics - During the 47th week of the year (November 17-23), there were 1,234 reported outbreaks of influenza-like illness across the country, with a positivity rate of 44.8% among respiratory samples from sentinel hospitals [5][6] - The positivity rate of influenza has raised public concern, with a clarification that this does not mean nearly half of the population is infected, but rather reflects the intensity of influenza activity [2][5] Regional and Temporal Trends - Except for a few provinces in East China, all other regions are experiencing moderate to high levels of influenza activity, with southern provinces reporting a positivity rate of 6.7% and northern provinces at 7.0%, both higher than the same period in previous years [6] - The current influenza season has started approximately one month earlier than in previous years [6] Demographics and Impact - The highest incidence of influenza cases is observed in the 5-14 age group, with a notable increase in outbreaks in schools and childcare facilities [7] - Vulnerable populations, including children under 5, the elderly over 60, pregnant women, and individuals with chronic diseases, are at higher risk for severe complications from influenza [4][7]

Core Viewpoint - The flu positivity rate among outpatient cases has approached 45%, indicating a significant prevalence of flu-like symptoms, but this does not mean that 45% of the general population is infected with the flu [1][3]. Group 1: Flu Positivity Rate and Symptoms - The flu-like cases refer to patients with respiratory symptoms such as fever and cough who visit outpatient services, and the positivity rate is derived from testing these specific cases [1]. - Among those with flu-like symptoms, the positivity rate for H1N1 (swine flu) exceeds 40%, while over 50% of cases are attributed to other pathogens like rhinovirus and respiratory syncytial virus [3][5]. Group 2: Symptoms in Different Age Groups - In younger populations, symptoms include significant fatigue and muscle aches, with high fever (38°C to 39°C) being common, while sore throat and cough are less pronounced [5]. - Children often experience high fever lasting several days, while elderly patients may not exhibit high fever but have a higher incidence of pneumonia, which can be overlooked [5][8]. Group 3: High-Risk Groups and Treatment - Individuals aged 65 and older are identified as a high-risk group for flu, and early diagnosis and treatment are emphasized to reduce severe outcomes [7][8]. - Antiviral medications should be administered within 48 hours of symptom onset to lower the risk of severe illness [8]. Group 4: Vaccine Efficacy and Infection - Flu vaccines are updated annually based on predictions from the World Health Organization, with effectiveness ranging from 30% to over 60% depending on the accuracy of the predictions [10]. - Even if vaccinated individuals contract the flu, the severity of the illness is generally reduced, and antiviral medications can still be beneficial [11][13].