Basic Pet Care

The History and Development of Vaccines

The History and Development of Vaccines

There is never a time in recorded history that infectious disease has not existed. In 1796, a country physician named Edward Jenner administered the first documented inoculation.

At that time, smallpox was a devastating epidemic, killing millions of people during the 18th century. Dr. Jenner had noticed that milk maids, who had been exposed to cowpox (as evidenced by pustules on the hands and arms), did not become ill from the smallpox outbreaks. Cowpox did not cause significant illness and death in humans, so Jenner famously inoculated a boy with pus from a cowpox lesion on a milk maid's hand and then was able to demonstrate the boy's resistance to infection from future exposure to smallpox 1,2.

Based on his pioneering thought, smallpox vaccine saved millions of lives that would have been lost to smallpox epidemics. For centuries, vaccination has been saving lives and today's vaccines are significantly improved over a pus sample.

Immune systems are amazing in the way they can respond to threats and then be able to "remember" markers that flag the infectious agent. The next time the threat attacks, the immune system quickly recognizes the marker and calls up the appropriate cells to fight. In the case of the cowpox and smallpox exposure, the viruses are so similar that an immune reaction to cowpox would trigger resistance to smallpox as well.

Vaccines take advantage of this extraordinary ability. They are able to teach the immune system how to recognize a specific threat without actually being at risk. They accomplish this feat through an inactivated threat (killed vaccine) or by utilizing the actual pathogen, modified to be harmless. The process is still very similar to the initial inoculation of the boy with the cowpox in 1796. There are different types of vaccines, but the goal of all of them is to reduce infection and subsequent death from the disease.

Whether human or pet, diseases with a high mortality and/or high incidence rate are the ones for which vaccines are developed. For pets, most vaccine protocols are based on the individual lifestyle, which can lead to different risk factors. Each pet should be treated as an individual, taking into account his/her history, age, species, breed, lifestyle, environment, and disease risk factors. Appropriate questions should be asked before deciding the vaccine choices.

The safety of vaccination has been called into question in recent years. The internet and social media smear vaccinations and blame them for a variety of health issues, ranging from cancer to autism.

Educated and informed medical sources have refuted many of these claims. By and large, vaccination is a very good idea and has saved countless animal and human lives. There are rare cases of allergic reactions to vaccines and these should be handled on an individual basis. Vaccination weighs the positives and safety against the small risks of side effects. It's important to learn about any vaccinations your pet receives, and how they can benefit both of your lives.

Random vaccination is not warranted and vaccine should be given based on risk because even though the chance of complications is small, if the chance of disease is smaller, one must find the balance.


  1. R.A. Meckel, "Levels and Trends of Death and Disease in Childhood, 1620 to the Present," in Children and Youth in Sickness and Health: A Handbook and Guide, ed. J. Golden, R.A. Meckel, and H.M. Prescott (Westport, Conn.: Greenwood Press, 2004), 3–24
  2. E. Jenner, Inquiry into the Causes and Effects of the Variolae Vaccine (London: Sampson Low, 1798), 45.