What is Vaccination?
Vaccination is the administration of a vaccine to stimulate a person's immune system to develop an adaptive immunity to a pathogen. Vaccines contain a weakened or killed pathogen, or an antigenic protein from the pathogen, which is sufficient to stimulate the body's immune system to recognize the pathogen and mount an immune response, thereby providing immunity to the disease. Vaccines can be prophylactic (to prevent or ameliorate the effects of a future infection by a natural or "wild" pathogen), or therapeutic (e.g. vaccines against cancer, which are used to treat existing disease).
What is in a Vaccine?
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. The agent stimulates the body's immune system to recognize the agent as foreign, destroy it, and "remember" it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.
Types of Vaccines
There are several types of vaccines available, including live attenuated vaccines, inactivated vaccines, subunit vaccines, toxoid vaccines, conjugate vaccines, and recombinant vector vaccines. Each type of vaccine works in a different way, and the type of vaccine used depends on the disease it is intended to prevent.
Side Effects of Vaccines
The most common side effects of vaccines are mild and temporary, such as redness and swelling at the injection site, fever, headache, and muscle aches. Serious side effects are rare, but do occur. It is important to talk to your doctor if you experience any side effects after receiving a vaccine.