In this third installment of Vaccines: What You Need to Know, we’ll compare the risks of vaccination with the risks of infection. For a review of how immune responses and vaccines work, please see our earlier posts How the Immune System Works and How Vaccines Work.
As described in our How Vaccines Work post, vaccines were developed to protect people from dangerous infections that have high rates of morbidity (illness) and mortality (death). These types of infections, which we refer to as high-risk infections, cause severe disease the first time you become infected. In today’s post, we’ll compare the risks of high-risk infections with the risks associated with vaccination, using pertussis (whooping cough) as an example. We’ll also link to some great (and credible) sites that debunk the association between the measles, mumps, and rubella (MMR) vaccine and autism.
Vaccination Works
Before we get into the precise risks of vaccination versus infection, it is important to understand the overall impact vaccines have had on public health. In the United States, vaccination has reduced the rates of illness from certain diseases like smallpox, diphtheria, and polio by 100%. For a great infographic on the impact of vaccines in the 21st century, click here. If you’re more of a numbers person, click here for a pdf of the data from the US Centers for Disease Control and Prevention (CDC) and the Journal of the American Medical Association (JAMA). Also see Figure 1, which shows the effect that vaccination has had on pertussis, a disease we’ll be talking about in more depth later in the post.
Figure 1. Reported Cases of Pertussis (Whooping Cough) in the United States by Year

Data are from the National Notifiable Diseases Surveillance System. Raw data can be accessed here.


