The flu vaccine is given every year starting around October and is available throughout the winter. Because the flu vaccine is now designed and made each year based on epidemiological speculation, the specific subtypes targeted by the flu vaccine vary from year to year, so the flu vaccine is required every year, year after year. Although the flu vaccine does not necessarily prevent 100% of flu attacks, it can generally reduce the severity of the disease. Therefore, it is better for susceptible people, such as children and the elderly, to get the flu vaccine to avoid a serious flu attack. In conclusion, influenza is quite a serious infectious disease that people are more familiar with and sometimes the fear is not as high. But in fact, influenza is a very serious infectious disease, and it is better for people who are relatively unfit to get the flu vaccine.