The origins of vaccines can be traced back to the Chinese Liao Dynasty in the 10th century. The ancient Chinese realized that people infected with smallpox would be immune to reinfection. This observation sparked the beginning of vaccines. Individuals previously infected with smallpox would preserve their scabs by drying them out, grinding them up into a powder, and blowing it up the nostrils of uninfected people through pipes.
Although not known at the time, they had devised a crude version of the modern vaccine we know today. But how did this work ? A vaccine simply works by introducing a weak version of pathogen into the body, which will stimulate the immune system to protect the body from future infections. In the case of the ancient Chinese, these scabs contained a weakened version of the smallpox virus which protected them from contracting the actual smallpox disease. So the concept of vaccination is not new. Now with advanced science, safety has a become a top priority.