A few weeks ago I did a two part series on the Anti-Vaccination movement and the rise of certain diseases (Read Part 1 & Part 2).  I did not discuss the benefits of vaccinating children in depth, partly because I had not found much research that discussed the positive side effects of vaccination.  How do you determine what could have, but didn’t, happen?

The New England Journal of Medicine found a way to do just that. They recently published a study that found that vaccination programs for children prevented more than 100 million cases of infectious disease in the United States.

A Study of the Positive Effects of Vaccination

The authors in the New England Journal of Medicine study gathered together all weekly surveillance reports of notable diseases found in the Morbidity and Mortality Weekly Reports and other journals for cities and states in the United States between 1888 and 2011.  This data included 87,950,807 reported individual cases of different diseases.  This is the raw data that was used to create a portrait of the effectiveness of vaccinations.

After combing through the data they focused on 8 diseases – polio, measles, rubella, mumps, hepatitis A, diphtheria, smallpox, and pertussis (whooping cough).  They picked these eight diseases was because all of these diseases have a vaccination and often caused epidemics.  They traced when the vaccinations were introduced and the effect that the introduction of these vaccinations had on thereafter. These were the results the team found for each disease:

1)      Smallpox – The vaccination was introduced into the United States in 1800 and by 1927 severe smallpox was eliminated but less severe versions continued until late 1940s when smallpox was eliminated.

2)      Polio – The inactivated Salk polio vaccination was licensed in 1955 which led to a decline in polio cases.  However, eradication of polio wasn’t achieved until 1979 after the live attenuated oral polio vaccine was introduced in 1961.

3)      Measles, Rubella, and Mumps – Have not been completely eradicated but there are significantly fewer cases and those cases are less severe.  Before vaccinations, measles, rubella, or mumps epidemics occurred yearly or every other year.  Various vaccinations for all three were released and led to a decline in the transmission of these diseases.

4)      Hepatitis A – The vaccination was licensed in 1995 and has led to a reduction in hepatitis A throughout the United States.

5)      Diphtheria –   The vaccination was licensed in 1914 but did not get used frequently until it became part of the DTP (diphtheria-tetanus-pertussis) vaccine in 1948.

The Bigger Picture: Implications of the Results

The study found that an estimated total of 103.1 million cases of these diseases had been prevented since 1924.  They also found that diphtheria, of which 40 million cases have been prevented since the inception of the vaccine, is the most prevented disease.  Measles is a close second with 35 million cases having been prevented, despite the late arrival of the vaccine in 1963.  Significantly, whooping cough is the only vaccine preventable disease that is consistently on the rise in the United States where it has had major increases in 2003-2005 and again in 2010.  In 2012 the largest whooping cough outbreak was reported since 1959 with more than 38,000 cases.

One reason that the disease elimination did not directly correlate with the introduction of the vaccine is that vaccines were introduced at various times and had differing effectiveness and adoption rates.  This is partly why there are more cases of Measles instead of Smallpox.

Vaccinations – Eradicating Disease and Saving Lives

As the chart above shows the introduction of vaccines led to fewer deaths.  Everything in this world poses a risk; however in this case the risk of vaccinating your kid is less risky than not.  As mentioned in previous blog post vaccination does not lead to autism nor is thimerosal dangerous to children.  In some case, like whooping cough, the vaccine doesn’t prevent contraction perfectly, but does prevent whooping cough death.  Vaccines are very helpful and allow society and people to live their lives.