Dr. Offit discussed the science behind the concern that vaccines cause autism and described how the media and the public came to understand this story.
How do vaccines work?
Vaccines are biological preparations that significantly help reduce the risk of serious infections and diseases by working to improve the body’s natural defense mechanism and thereby developing immunity. Every vaccine contains a component that imitates a particular infection, which therefore activates the body’s immune system without actually causing the full onset of the disease. The body’s white blood cells (macrophages, B-lymphocytes, and T-lymphocytes that are part of the immune/lymphatic system) recognize the “intruder” component, and work to destroy it. After this process, all that is left behind are “memory” T-lymphocytes and B-lymphocytes that “remember” this version of the pathogen and how to fight it off, should a person ever encounter that particular disease in the future.
What kinds of vaccines are available today?
There are 5 different types of vaccines:
- Live, Attenuated Vaccines – fight viruses by containing a weakened version of the living virus (ex. measles, mumps, rubella (MMR) and varicella (chickenpox) vaccines)
- Inactivated Vaccines – fight viruses by containing a killed/inactive version of the virus (ex. polio vaccine)
- Toxoid Vaccines – prevent bacterial diseases by arming the body with a weakened version of the toxin that those bacteria produce (ex. diphtheria & tetanus (DTaP) vaccine)
- Subunit Vaccines – contain only the essential antigens of the virus or bacteria in order to fight off infection (ex. pertussis/whooping cough vaccine)
- Conjugate Vaccines – fight off bacteria with an outer coating surrounding their antigen that acts as a “disguise” by creating a linkage that helps an immature immune system react to this coating to develop an immune response (ex. Hib vaccine)
Today, children receive 14 different vaccines according to an established vaccination schedule recommended by the FDA and CDC. In addition to testing how the vaccine works prior to releasing it into the general population, they also test how it interacts with other existing vaccines in order to come up with this safe schedule. Also, although there are clearly a lot of vaccinations and injections involved, the actual number of immunological components in these vaccines is actually relatively small.
Still not convinced? See the following infographic on the timeline for vaccine approval:
Resources:
Offit, Paul A. Deadly Choices: How the Anti-vaccine Movement Threatens Us All. New York: Basic, 2011.
http://sites.jmu.edu/gbio103/files/2015/02/IMG_0001_2.jpg
http://www.cdc.gov/vaccines/hcp/conversations/downloads/vacsafe-understand-color-office.pdf