How to prevent influenza in children? The best way to prevent influenza in children is to

Sources of infection and routes of transmission

Patients are the main source of infection, especially mild patients and latently infected people, because they are not easy to be discovered and have a wide range of activities. Healthy people with the virus excrete very little virus and it is very short, so it plays a small role in spreading the disease. At the end of the incubation period, the virus can be excreted from the patient's respiratory secretions and directly infect people from person to person through droplets. Most viruses are most contagious within 3 days of onset, when the fever subsides, or they are no longer excreted after a week. Droplets contaminate hands, electrical appliances, and clothing, and can also be transmitted indirectly, but because the influenza virus survives in the air for no more than 30 minutes, the opportunity for transmission is from antigen-confirmed animal (pig, horse, bird) influenza viruses and human influenza viruses are homologous. Animal influenza can be transmitted to the human population, but most of them play a certain role as a triggering factor or long-distance transmission in the early stages of the epidemic.

Immunity

They are generally susceptible to influenza viruses and are immune to the same viruses after infection, but the duration is only 8 to 12 months, not more than 2 years. There is no cross-immunity between influenza A viruses and their variability is large. Therefore, humans often suffer from influenza repeatedly, which can easily cause epidemics. ① Systemic resistance: related to the level of specific antibodies in the blood. The levels of neutralizing antibodies and hemagglutination inhibition antibodies are usually parallel, reaching a peak 2 weeks after the onset of the disease and then gradually declining, and falling to pre-disease levels after 8 to 12 months. Antibodies penetrate into tissues and their secretions from the blood to prevent viral invasion and reproduction. Newborns can obtain passive immunity from their mothers, which decreases significantly from the 2nd to 3rd month and disappears completely at 7 months. Because children of different age groups are exposed to different influenza virus strains, their blood antibody composition is also different from cellular immunity. nk increases cell killing and interferon activity; ② Local resistance: Infections are mostly local mucosal surface infections of the respiratory tract, the virus does not invade the bloodstream, and the incubation period is short. The effect of serum antibodies in preventing infection is limited and not lasting, and local immunity is more important. After viral infection, the local mucosa quickly secretes specific SIGA. In addition, the local inflammatory response and increased mucociliary movement increase the secretion, which plays a non-specific local protective role against viral invasion. Moreover, after viral infection, the local respiratory epithelial cells are damaged and metamorphosed, and the virus is not easy to invade again in the short term, which also plays a certain protective role.

age

Children and adolescents are more likely to suffer from this disease, with the highest incidence rate among those aged 5 to 20 years. Infants under 4 to 5 months are rarely infected. When a new subtype is prevalent, the incidence rate of each age group is close, but the infection rate of children aged 5 to 14 years is still close to 50%. In the local epidemic years, the infection rate of the general population is about 10%. Children, the elderly and pregnant women are prone to severe illness and have a high mortality rate. Most children with influenza B and C are reported to have influenza C before the age of 10. It is reported that most children have influenza C before the age of 10.

season

Generally speaking, temperate and cold temperate influenza are prevalent in late winter and early spring. The disease is severe in winter. Tropical and subtropical influenza can be prevalent in any season, but there are more rainy seasons and they can also be prevalent in summer. For example, it was prevalent in Beijing in July 1968 and in Shanghai in the summer of 1981.