Vaccine

A vaccine is a biological method that provides active acquired immunity to a particular infectious disease. A vaccine is made from a disease-causing microorganism or microbe, its toxins, or one of its surface proteins. The agent stimulates the body's immune system to recognize the agent as a threat, and combat it using the body's natural defense mechanisms. The science of vaccine development and production is termed vaccinology.

The administration of vaccines is called vaccination which is the most effective method of preventing infectious diseases. Some diseases like smallpox are completely eradicated. The World Health Organization (WHO) lists 25 different preventable infections by vaccine.

The first vaccine was for smallpox by Edward Jenner in 1798 and that led to other first generation vaccines for other poxes, cholera and anthrax.

In 1881, to honor Jenner, Louis Pasteur proposed that the terms should be extended to cover the new protective inoculations then being developed, which covered second generation vaccines for diseases like yellow fever, diphtheria, measles, mumps, and rubella.

RNA and DNA vaccines are third generation vaccines. mRNA vaccines were developed in the year 2020 with the help of Operation Warp Speed and massively deployed to combat the COVID-19 pandemic.

In 1900, life expectancy was around 49. Communicable diseases such as pneumonia, influenza, tuberculosis, diphtheria, smallpox, pertussis, measles, and typhoid fever were the leading causes of mortality. Vaccination, together with improved hygiene practices and antibiotics, have played an essential role during the last century in eliminating most of the mortality from infectious diseases. Today, life expectancy is about 78 and diseases such as heart disease, stroke, cancer, diabetes, Alzheimer, and other neurodegenerative diseases are the leading causes of death.