Vaccines have helped save millions of lives by protecting people from once-deadly diseases (examples include smallpox and typhoid). Today, vaccines are regularly administered from infancy, though older children are frequently given “booster shots.” Adults can also be given vaccines, though some should not be administered during pregnancy. Vaccines are typically administered through an injection, though there are oral vaccines and even powder or aerosol vaccines.
Vaccines work by introducing a small amount of the virus, bacteria or toxin that trigger a disease to the body. The “dose” is too small (and the toxin is usually weakened or even killed) so there is no danger of the vaccine actually escalating into actual illness. Instead, it triggers the body’s immune system, particularly the B-cells.
B-cells are the body’s soldiers. These fight the virus, bacteria or toxin, forming the antibodies that will effectively destroy the “enemy.” The antibodies remain in the body, so if a person is exposed to a similar microorganism, he or she already has the defenses ready.
Some vaccines give a lifetime immunity against a disease. There are those that only work for a specific time, though, so to extend protection the person has to get booster shots.
Some microorganisms like viruses mutate so quickly that the first vaccines are virtually useless. That’s why it’s recommended to get a flu vaccine every year.
While the medical associations have come up with a recommended list of vaccines for all children, there are some vaccines that are only required for specific situations. For example, a person who travels to a country with a high incidence of malaria will be required by the Embassy to get a malaria vaccine before being issued a visa.