Part 1: How vaccines are made and how they work
In 2008, WHO estimated that 1.5 million of deaths among children under 5 years were due to diseases that could have been prevented by routine vaccination. This represents 17% of global total mortality in children under 5 years of age.
Hygiene, proper nourishment and sanitary conditions make for a healthy community, with lowered incidence of infectious disease, but since much of this is lacking in developing countries, vaccination is very helpful to giving the immune system a boost.
We can thank scientists, physicians and engineers for their work in understanding the immune system and how to make it work for us against disease by using vaccinations.
Famous Scientists in the field of vaccine development
Most of you have heard the stories of how vaccinations came about starting with Edward Jenner (cowpox) to Louis Pasteur (rabies) then to Jonas Salk and Albert Sabin (polio). A story you may not have heard in school was about Maurice Hilleman and his team at Merck who developed several dozen of the most common efficacious and cost-effective vaccinations and has saved millions of lives. I highly recommend this book by Paul Offit, Vaccinated: One Man’s Quest to Defeat the World’s Deadliest Diseases
There are many good books and websites on the lives Jenner, Pasteur, Salk and Sabin as well.
For a quick, fun way to learn about scientists who have made vaccination discoveries, visit The History of Vaccines to play this matching game of pioneers in vaccine development.
How Vaccines Work
Vaccines manipulate the immune system of the recipient. Thus, to understand how vaccines work (or how to create new vaccines), we must first understand how the immune system prevents and fights infections. It is also a good idea to understand how infectious agents cause disease. This to me sounds like an entire college career!
Visit The History of Vaccines to go to a colorful tutorial to learn more about how vaccines work. Go ahead and check it out!
The goal of vaccination is to stimulate the adaptive immune system to make memory cells that will protect the vaccinated person against future exposure to a pathogen, without causing the symptoms of the disease.
There are several types of vaccines which can stimulate the immune system to provide memory and protect against future exposure to a pathogen.
According to the CDC, the GENERAL RULE is:
The more similar a vaccine is to the disease-causing form of the organism, the better the immune response to the vaccine.
What are the requirements for an effective vaccine?
They vary according to the nature of the infecting organism.
For extracellular organisms, antibodies against the organism (or part of it, some antigen) prove to be the most adaptive mechanism of host defense, whereas, for control of intracellular organisms (such as polio virus) an effective immune cell (CD8 t-lymphocyte) response is also essential.
The ideal vaccination provides host defense at the point of entry of the infectious agent; stimulation of mucosal (these are the moist nose, mouth, eye surfaces) immunity is an important goal.
Effective protective immunity against some organisms requires the presence of pre-existing antibody at the time of exposure to the infection, and booster shots are a great way to boost the presence of antibody.
Features of an effective vaccine
|Safe||Vaccine must not itself cause illness or death|
|Protective||Vaccine must protect against illness resulting from exposure to live pathogen|
|Gives sustained protection||Protection against illness must last for several years|
|Induces neutralizing antibody||Some pathogens (such as poliovirus) infect cells that cannot be replaced. Neutralizing antiboody is essential to prevent infection of such cells.|
|Induces protective T cells||Some pathogens, particularly intracellular, are more effectively dealt with by cell-mediated responses|
|Practical considerations||low cost per dose, biological stability, ease of administration, few side-effects|
Want to learn more about how vaccines are made? Go to the tutorial at The History of Vaccines to learn more!
Listed here are the types of vaccines that can be produced based on the organism and type of response required.