It is widely believed that vaccination is the most successful medical breakthrough in the history of medicine and public health though there is another group of people who feel otherwise. It can not be claimed that every vaccine is without a fault. Some vaccines have saved lives whereas some have taken lives.
The term "vaccine" is taken from "vacca," a word in Latin meaning "cow." The reason for this unique name comes from the following historical incident. Edward Jenner, a physician by profession noticed a unique phenomenon that the milkmaids who had contracted cowpox were later immune to smallpox. In 1796, to put his observation into test, he took some infected cowpox matter and exposed an otherwise healthy boy through a cut in his arm. The boy then caught cowpox. After he recovered from this simulated disease, he then exposed him to smallpox via an injection, but the boy remained healthy. He invented the first vaccine which was named after cows.
How vaccines work
Vaccines are used to expose the immune system to harmful antigens and teach the body how to fight back. After fighting off the vaccine, the body retains a lasting memory of how to fight off that particular type of attack. The process of vaccination administers a weakened or dead pathogen into the bloodstream. Once the antigens are identified, the B-cells or lymphocytes in our body go to work. It is these cells that are responsible for fighting disease-causing pathogens. Once the B-cells are stimulated into activity, the immune system develops proteins that circulate in the blood. These proteins are called antibodies. This helps the body in learning about the agent in advance and preparing to defend itself.
When the body is invaded by that particular pathogen after the vaccination, the immune system is in a better state to face it head on. The vaccine provides just enough of these antigens for the body to recognize them and complete the immune response process. When the actual disease infects a person, the antibodies multiply many times until the disease is fully controlled. The body preserves these antibodies for future to fight off the disease when exposed to. Unfortunately, antibodies are disease-specific, so antibodies acquired for a specific antigen will be useless if faced with other diseases.
There are two main groups of vaccines: live-attenuated vaccines and inactivated vaccines.
Live-attenuated means alive, but very weak. These vaccines are made when the virus is weakened in a laboratory process to such a level that they reproduce only about 20 times in the body. In inactivated vaccines the bacteria is completely killed using a chemical called formaldehyde. The strength of these vaccines are comparatively weak, so the immunity wears off over time.
How vaccines are administered
Most vaccines are administered in the form of a hypodermic injection and some are liquids that are consumed by mouth. However, some vaccines are inhaled as aerosols or powders. The majority of vaccines contain viruses or bacteria that have been weakened or killed. Others contain inactivated antigens. In their altered states, vaccine pathogens are typically safe and unable to cause disease.
Are vaccines still relevant?
Vaccines help a living body to prepare in advance for fighting with potentially deadly diseases. Essentially, a particular vaccine gives the body a preview of a bacterium, virus, or toxin, unique to that disease. A lot of young parents are worried about giving their babies so many shots, thinking that these will overwhelm the immune system of the baby. We may argue that vaccines aren't necessary anymore because all the diseases are gone anyway. According to the CDC, if we stopped vaccinating, many diseases that are now unknown would come back with a vengeance. It may look that a vaccine can give the disease it's supposed to prevent, but the reactions are very minor and much better than coming down with a full-blown killer disease.