Vaccination is the administration of a vaccine to help the immune system develop protection from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism.

The first disease people tried to prevent by inoculation was most likely smallpox, with the first recorded use of variolation occurring in the 16th century in China. It was also the first disease for which a vaccine was produced. Although at least six people had used the same principles years earlier, the smallpox vaccine was invented in 1796 by English physician Edward Jenner. He was the first to publish evidence that it was effective and to provide advice on its production. 

Edward Jenner is considered the founder of vaccinology in the West after he inoculated a 13 year-old-boy with vaccinia virus (cowpox), and demonstrated immunity to smallpox. In 1798, the first smallpox vaccine was developed. Over the 18th and 19th centuries, systematic implementation of mass smallpox immunisation culminated in its global eradication in 1979.

Louis Pasteur’s experiments spearheaded the development of live attenuated cholera vaccine and inactivated anthrax vaccine in humans (1897 and 1904, respectively). Plague vaccine was also invented in the late 19th Century. Between 1890 and 1950, bacterial vaccine development proliferated, including the Bacillis-Calmette-Guerin (BCG) vaccination, which is still in use today. 

In 1923, Alexander Glenny perfected a method to inactivate tetanus toxin with formaldehyde. The same method was used to develop a vaccine against diphtheria in 1926. Pertussis vaccine development took considerably longer, with a whole cell vaccine first licensed for use in the US in 1948.

Smallpox was a contagious and deadly disease, causing the deaths of 20–60% of infected adults and over 80% of infected children. When smallpox was finally eradicated in 1979, it had already killed an estimated 300–500 million people in the 20th century.

In 1974 the WHO 1974 the WHO adopted the goal of universal vaccination by 1990 to protect children against six preventable infectious  diseases: measles, poliomyelitis, diphtheria, whooping cough, tetanus, and tuberculosis.

In the 1980s only 20 to 40% of children in developing countries were vaccinated against these six diseases. In wealthy nations the number of measles cases had dropped dramatically after the introduction of the measles vaccine in 1963. WHO figures demonstrate that in many countries a decline in measles vaccination leads to a resurgence in measles cases. Measles are so contagious that public health experts believe a vaccination rate of 100% is needed to control the disease.

Despite decades of mass vaccination polio remains a threat in India, Nigeria, Somalia, Niger, Afghanistan, Bangladesh and Indonesia. By 2006 global health experts concluded that the eradication of polio was only possible if the supply of drinking water and sanitation facilities were improved in slums.

The deployment of a combined DPT vaccine against diphtheria, pertussis (whooping cough), and tetanus in the 1950s was considered a major advancement for public health. But in the course of vaccination campaigns that spanned decades, DPT vaccines became associated with high incidences of side effects. Despite improved DPT vaccines coming onto the market in the 1990s DPT vaccines became the focus of anti-vaccination campaigns in wealthy nations. As immunization rates fell outbreaks of pertussis increased in many countries.

What we do know is that COVID-19 has caused very serious illness and death for a lot of people. So, If you get COVID-19, you also risk giving it to loved ones who may get very sick. Getting a COVID-19 vaccine is a safer choice because getting the maximum population vaccinated in the country is the best way to keep everyone safe from the deadly coronavirus.

In the case of COVID-19, All COVID-19 vaccines bring  coronavirus to heel, humanity’s centuries of success in developing vaccines means that today few people doubt that a safe, effective inoculation can be found. And as novel viruses continue to emerge, the vaccine arsenal will inevitably grow.