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How Do Vaccines Work?

There are Different Ways to Induce Immunity Against Disease

Aug 11, 2009 Kenneth Rosen

Vaccinations are one of the truly remarkable public health victories of the modern era. How exactly does one make a vaccine and how do they protect against disease.

Prior to the advent of vaccines, tens of thousands of people were severely affected or killed by diseases such as smallpox, polio, whooping cough (pertussis), German measles (Rubella), measles (Rubeola) and, of course, influenza. Vaccine administration can prime the body’s defense systems (the immune system) to be prepared to fight off the effects of infection with a given disease causing organism. But not all vaccines are made to activate the immune system by the same means.

Vaccination or Immunization Basics

The human immune system is a remarkable thing. Faced with having to deal with an invading threat to the body and its overall health, it has numerous ways to fight these foes, using different specialized cells such as T and B lymphocytes and macrophages. Perhaps most remarkable of all, the immune system has a “memory”. If it has seen a particular invader previously, or has been tricked into thinking that it did, it remembers how to fight it off and can mount a defense much more rapidly. In vaccinations, the immune system is exposed to non-disease producing components of a normally toxic invader and can train its “memory” so that it will be ready to fight off the actual offender if challenged at a later time.

How Did Vaccines Start?

In the late 1700s, a British physician, Edward Jenner, noticed that milkmaids never seemed to suffer from smallpox, which was a scourge at that time in history. He also noticed that the milkmaids were being exposed to cowpox, which would cause a much milder illness. Jenner surmised that perhaps cowpox and smallpox might be related diseases and that exposure to the milder cowpox could be protective against the much more deadly smallpox. He was correct.

Using material that he extracted from the cowpox blisters on milkmaids hands and arms, he inoculated others with the extracts and found that they were protected when there were outbreaks of smallpox. He did not even know, nor did anyone at that time, that these diseases were caused by viruses, and that these two viruses were very similar. Exposure to the mild one (cowpox) protected against disease from the much more deadly one (smallpox). As testament to this finding, the word vaccination is derived from Vacca , the Latin word for Cow.

What are Vaccines Made Of?

A vaccine can be any of a number of different components introduced into the body that will allow the immune system to mount an immune response that will provide protection when challenged with the actual disease causing agent. In some cases, a vaccine contains purified proteins that are normally made by an offending bacterial or viral invader. The presence of the specific protein alone can prime the immune system to respond so that if it sees the protein again, but perhaps now associated with the actual offending intruder, it can quickly fight it off. Unfortunately this approach does not routinely work for all infectious challenges.

For some vaccines in use today, it is not uncommon for them to contain what are known as “live, attenuated” viruses. In this case, the inoculation contains a functional virus that can still replicate but has been grown and shown to be unable to cause severe disease. It can however, still trigger the immune system so that it would recognize and fight off the more virulent forms if exposed. Other vaccines may contain killed or inactivated versions of the virus or bacteria that cause the disease. But the structures that they present to the immune system are still intact enough to allow for the body to develop immunity.

The advent of vaccines has either eliminated or dramatically reduced the burden of numerous diseases on the human population. While it is true that for some diseases generating an effective vaccine can be extremely difficult, vaccines rank very high, along with antibiotics and effective public health measures such as sanitation, in removing the scourge of widespread fatal disease outbreaks.

Read this informative article by Dr. Stefan Riedel about Dr. Edward Jenner and his work against smallpox.

The copyright of the article How Do Vaccines Work? in General Medicine is owned by Kenneth Rosen. Permission to republish How Do Vaccines Work? in print or online must be granted by the author in writing.

Smallpox Virus