Entering the cold winter, people are more susceptible to catching a cold due to the impact of temperature. This year is no exception, as winter is the peak season for influenza. So, what are the ways in which influenza spreads?
Winter is the peak season for influenza
Every year during winter and spring, influenza outbreaks occur, and this year is no exception. Many parts of China have already entered the peak season for influenza. The latest report from the National Influenza Center (as of the 4th) shows that most provinces in mainland China have entered the winter and spring influenza season, and the activity level is continuing to rise. The number of outpatient respiratory infections in multiple cities is increasing, indicating that influenza is gradually reaching its peak.
Influenza is different from common colds as it is highly contagious. In addition to the symptoms of a common cold, it is often accompanied by high fever of 39-40 degrees Celsius, accompanied by headache, muscle pain, and fatigue. In severe cases, complications such as pneumonia, otitis media, myocarditis, meningitis, or encephalitis may occur.
Children and the elderly are more susceptible to this wave of influenza. The children's hospital in Yuexiu District, Guangzhou, is overcrowded, with some patients coming to see doctors with their siblings. Since December, the number of influenza-like cases treated in the hospital has continued to rise, with an increase of at least 10% compared to November, with influenza A being the main strain.
Ways in which influenza spreads
Influenza patients and asymptomatic carriers are the main sources of infection. The virus is infectious from the end of the incubation period until the acute phase, with the highest infectivity during the first 2-3 days of illness. In adults and older children with seasonal influenza (without complications), the virus generally continues to be shed in respiratory secretions for 3-6 days.
Adult patients who are hospitalized can continue to spread infectious viruses for one week or longer after onset. It has been found that long-term shedding (1-3 weeks) is common in infants with influenza or cases of human H5N1 avian influenza. In addition, patients with immunodeficiency diseases such as AIDS may experience prolonged viral shedding periods.
The main mode of transmission for influenza is through airborne transmission, such as droplets. When entering crowded places during the peak season of influenza, protective measures should be taken, such as wearing masks. Only masks made of 8-10 layers of thick gauze can effectively block the virus. Masks should not be worn inside out and should be folded tightly after removal. It is best to boil them in hot water or soak them in disinfectant and dry them before reuse.
Another mode of transmission is through contact with influenza patients, such as shaking hands or touching objects used by influenza patients. To prevent transmission, frequent handwashing is necessary, and alcohol can be used as a daily disinfectant. Follow the five-step handwashing method: before meals and after using the restroom, after sneezing, coughing, and cleaning the nose, and after returning from outside, make sure to wash hands according to the prescribed procedure.
Characteristics of influenza outbreaks
The characteristics of influenza outbreaks include sudden onset, rapid spread, reaching a peak within 2-3 weeks, high incidence, short epidemic period, and transmission along transportation routes. Generally, the outbreak will naturally stop after 3-4 weeks, with high morbidity but low mortality rates.
The pattern of outbreaks usually starts in cities and then spreads to rural areas, starting with collective units and then spreading to individual residents. Influenza A often causes explosive outbreaks or even global pandemics, with small outbreaks occurring every 2-3 years. Based on the analysis of the four major pandemics that have occurred worldwide, a major pandemic usually occurs every 10-15 years. Influenza B tends to cause explosive or small-scale outbreaks, while influenza C mainly occurs sporadically.
The peak season for influenza can occur in all four seasons, with the northern regions of China generally experiencing the peak during winter and spring, while the southern regions have year-round outbreaks, with peaks occurring more frequently in summer and winter.
