The advancement of modern medicine helped us to live longer than ever before. Until recently, deaths at or around the age of 30 were very common. The smallpox, for example, was considered one of the deadliest diseases known to humans. Until the smallpox vaccination was found in 1796, the smallpox virus killed 3 out of every 10 people who contracted the disease. But what are vaccines? And how do they work in the human body?

A vaccine is substance used to stimulate the production of antibodies and to provide immunity against one or several diseases. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins.
When the body is exposed to the harmful agent found inside the vaccine, the immune system immediately responds by producing antibodies specific to the disease-causing organism. This provides immunity without actually inducing the disease.

Vaccine development is a long and complex process often lasting several years.
– The process begins by doing the research and developing of the appropriate antigens that might help prevent or treat the disease.
– Preclinical studies test the vaccine on animals to assess the safety of the vaccine, and to make sure that the vaccine isn’t harmful or deadly.
– Clinical development is a three-phase process with an increasing number of or people who receive the trial vaccine. And it ends when the vaccine is given to thousands of people and is fully tested for efficacy and safety.
– The final stages involve regulatory approval and licensure, manufacring and distribution.