打预防针是为了防止人体患上各种流行病。流行病指的就是会在人群中相互传染

打预防针是为了防止人体患上各种流行病。流行病指的就是会在人群中相互传染的疾病，如流行性感冒、霍乱症等。

Results (English) 1:

Vaccination is to prevent human suffering from various epidemics. Epidemiology refers to the will of another infectious disease in the population, such as influenza, cholera psychosis.

Results (English) 2:

Vaccinations are used to prevent the body from contracting epidemics. Epidemics refer to diseases that can be transmitted to each other in a population, such as influenza, cholera, etc. ...

Results (English) 3:

The purpose of vaccination is to prevent the human body from suffering from various epidemics. Epidemics refer to diseases that can infect each other among people, such as influenza, cholera, etc.