Vaccination: Meaning, Definition and List of Most Important Vaccines

Vaccine is an immunity boosting preparation that typically contains weakened or killed pathogen against which the immunity is required. Human body is capable of producing antibodies to fight a large number of disease causing agents such as viruses and bacteria. Through the vaccine weakened / dead pathogen is administered inside our body. Presence of pathogen activates the defense mechanism of human body. To defend against the pathogen our body generates the antibodies. The good thing is that, once produced, antibodies remain in our bodies for ever. Therefore, in a way, our body becomes educated in dealing with the pathogen. If the same pathogen enters in our body in the due course of life, our body will be able to protect itself because it already has the antibodies against the pathogen.

So, a vaccine basically mimics an attack of disease on our body, without actually making us sick! Isn’t it a clever approach?!

Who Invented the First Vaccine?

Smallpox vaccine was the first vaccine to be produced. British physician Edward Jenner invented and patented the smallpox vaccine in 1796. Many people before Jenner had worked on the same principal. However, Jenner was the first person to publish the evidence that the idea of vaccine actually worked. He also published the advice on how to produce the vaccine. Therefore, Edward Jenner usually gets all the credit of inventing vaccination.

Vaccination is the term used for administering the vaccine. Vaccination is also known as inoculation and immunization.

Meaning of the Terms Vaccine and Vaccination

In the times of Edward Jenner, smallpox epidemic had spread like wildfire. It affected humans as well as animals. Cows were affected by cowpox — a much milder disease than smallpox. Jenner gave the name Variolae vaccinae to cowpox. Later on Jenner published his findings on how cowpox virus can be used to create immunity in humans against smallpox virus. In 1881, Louis Pasteur proposed that the term vaccine should be used to describe the new protective inoculations to honor Jenner.

Most Important Vaccines in History of Mankind

Needless to say all vaccines are important as they save us from diseases. However, some of the vaccines have been specially important as they prevented epidemics and pandemics. Following are some of the vaccines that certainly deserve a mention:

Smallpox Vaccine

Smallpox vaccine is distinguished for the obvious reason of being the first vaccine ever produced. But that’s not all. Smallpox vaccine helped eradicating smallpox — one of the most horrifying diseases man has ever known. According to D.A. Henderson, smallpox is estimated to have killed up to 300 million people in the 20th century and around 500 million people in the last 100 years of its existence. Smallpox was finally eradicated in 1977.

BCG Vaccine

BCG vaccine is used for preventing tuberculosis (TB). It was discovered by Albert Calmette, a French physician and bacteriologist, and his colleague, Camille Guérin, a veterinarian. Both Albert Calmette and Camille Guérin repeatedly subcultured the Mycobacterium bovis bacteria 239 times over a period of 13 years. With each subculture the virulence of bacteria got reduced. Finally they were able to isolate sufficiently weakened bacteria that it would not cause tuberculosis in lab animals. BCG was first used in humans in 1921. The vaccine was named after its inventors.

Polio Vaccine

In 1950s there was a saying that Americans were afraid only of two things: a nuclear bomb retaliation and polio. Such was the terror of this crippling disease. Poliovirus usually spreads through infected fecal matter entering the mouth. Once a person is infected, there is no cure for it. According to World Health Organization (WHO), there were 350,000 cases of polio in the year 1988.

When asked, “Who owns this patent (of polio vaccine)?”, Dr. Salk replied, “Well, the people I would say. There is no patent. Could you patent the sun?”

Dr. Jonas Salk developed the first polio vaccine. Dr. Salk prepared the vaccine that was injected into children. This vaccine contained the dead polio virus. In 1954, he ran a massive trial program with 1.8 million children participating as volunteers — called the polio pioneers. Dr. Salk’s polio vaccine was announced as safe and effective on 12 April 1955.

Dr. Albert Sabin, a contemporary of Dr. Salk, also worked on a polio vaccine. Taking a different route, he used the weakened virus in his vaccine. Dr. Sabin’s vaccine was given through the mouth. Later on, in 1980, when the polio eradication program started at global level, Dr. Sabin’s oral vaccine was used to vaccinate children.

DPT Vaccine

Licensed in 1949, DPT is a combination of vaccines against three disease: diphtheria, pertussis, and tetanus. All three of these diseases are caused by bacteria. Tdap, a variant of DPT vaccine is given during the pregnancy to help protect the baby even before birth. In the United States, five doses are given to the child between the age of two months and 15 years. Booster shots for adults are also advised every ten years.

HPV Vaccine

World Health Organization recommends Human papillomavirus (HPV) vaccines as part of routine vaccinations in all countries of the world. These vaccines are closest to what we have got for a cancer vaccine. It is estimated that HPV vaccine may prevent 70% of cervical cancer, 80% of anal cancer, 60% of vaginal cancer, 40% of vulvar cancer and possibly some mouth cancer.

MMR Vaccine

MMR vaccine give us immunity against three viral diseases: measles, mumps, and rubella. Two doses of MMR vaccine are recommended. First dose is given to children of 9 to 15 months of age. Second dose is given at 15 months to 6 years of age. According to Centers for Disease Control and Prevention (CDC), after two doses, 97% of people are protected against measles, 88% against mumps, and at least 97% against rubella. Measles resulted in 2.6 million deaths per year before vaccination became common around the world.

COVID-19 vaccine

So far, no vaccine is available for Covid-19 disease caused by SARS-CoV-2 virus. This disease has become a pandemic and has killed thousands of people around the world. Efforts at large scale are going on to develop a vaccine against the virus. The on-going efforts are an evidence of the importance of vaccines in our lives.