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Home » Why we vaccinate–103 million cases of diseases averted since 1924

Why we vaccinate–103 million cases of diseases averted since 1924


For New Year’s Day, I’m republishing the top 10 articles I wrote in 2013. Well, actually top 9, plus 1 from 2012 that just keeps going.

#10. This article was published on 3 December 2013, and has had over 5000 views. It’s one of my favorite because it shows, with scientific evidence, that the trope pushed by the vaccine deniers that better sanitation, food, and medicine reduced the mortality from these diseases. But we know it’s the vaccines, and we have brilliant science to support that fact.

One of the tropes of the antivaccination world is that vaccines didn’t stop diseases. They give credit to everything from modern medicine to better food to better sanitation. Some of the credit they give is ironic since many vaccine deniers hate most aspects of modern medicine and believe that food was better 100 years ago. You can never get enough of the contradictions and hypocrisy of the antivaccine crowd.

I think it becomes easy to dismiss the value of vaccines in ending widespread disease because almost anyone writing today about vaccines has no memory of ubiquitous and deadly epidemics of diseases. We’re almost at a point in our culture that if Twitter doesn’t report it, it didn’t happen, so infectious diseases are something that happened back when humans lived in caves, prior to the advent of social media. I happen to have been born right near the end of widespread epidemics of infectious diseases, so I don’t remember any epidemics personally, though I recall a few classmates in high school who had a few effects from polio and other diseases. Culturally, we have forgotten our past with respect to diseases.

So science helps us remember the past. A new study, published in the New England Journal of Medicine and led by Willem G. van Panhuis, MD, PhD, of the Department of Epidemiology at the University of Pittsburgh, closely examined the patterns of infectious diseases in the US and the effects of licensing of vaccines on those diseases. The study aimed to provide us with visibility to the number of cases of each disease, over time, that were prevented by vaccines since their introduction.

As a result of this research, the authors found that about 103 million cases, of just seven infectious diseases, were prevented since vaccines for each of those diseases were licensed and introduced in the USA. These 103 million cases would have appeared despite improvements in medicine (of course without vaccines, one of the greatest tools of medicine), safer food and better sanitation (or whatever vaccine deniers believe, without evidence, ended infectious diseases).

This was not an easy study to set up. The researchers digitized all of the data, from 1888 to 2011, that was reported weekly to the Centers for Disease Control and Prevention (CDC) (or other Federal agencies, like the US Public Health Service and US Marine Corps who had responsibility for the data prior to the existence of the CDC). One of the major responsibilities of the CDC is to track morbidity and mortality from diseases (and other activities like accidents), but the process was ongoing before the CDC existed.

This was a massive amount of information–several hundred thousand individual data points that had to be read, entered into a computer, checked for errors, then analyzed. The data, Project Tycho,  is available online. 

The authors examined eight vaccine-preventable diseases: smallpox, polio, measles, rubella, mumps, hepatitis A, diphtheria, and pertussis. For seven of the diseases, the authors estimated the number of cases of the disease that would have been prevented since the specific vaccine was launched by subtracting the weekly cases of the diseases in the years after the launch of the vaccine from the total expected based on historical numbers (along with changes in population). Smallpox was removed from the analysis since the vaccine was introduced in the early 1800’s, and vaccination rates were unknown in early years.

For the 2010 calendar year, the researchers estimated the number of cases prevented for each disease:

  • Polio: 25,000
  • Measles: 900,000
  • Rubella: 84,000
  • Mumps: 270,000
  • Hepatitis A: 35,000
  • Diphtheria: 700,000
  • Pertussis: 350,000

conquest-disease-vaccinesThat’s 2.36 million people who were spared serious diseases with serious consequences in 2010 alone. The costs of emergency treatment, physicians visits, ICU, medications, and other more nightmarish costs would have bankrupted those families and the country. Economic consequences aside, vaccines prevented the heartbreak and fear engendered by epidemics of these diseases. In fact, the researchers determined that over 20 million cases of vaccine preventable diseases were avoided in the last 10 years alone.

Within the data, there were some impressive results from the use of vaccines. For example, the authors stated that measles cases dropped dramatically after the vaccine was introduced, but it took longer for rubella and mumps cases to decline after those vaccines. The large drop for these diseases came after 1978, when the combined measles-mumps-rubella (MMR) was introduced.

For example, over 40 million cases of diphtheria, a disease that used to kill about 50% of people who got the disease, have been averted through the introduction of the vaccine in 1924. Over 35 million cases of measles, a serious disease where 1-2 out of 1,000 children die, have also been stopped by vaccines. 

Some of the infectious diseases studied, specifically measles, hepatitis A, diphtheria, and pertussis, had rates that varied substantially before vaccines were introduced. This variance was probably related to changes in sanitation, hygiene, demographics, or other related factors. However, once the vaccines were introduced the rates dropped permanently and significantly, with little variance.

One last, but important, item: the 103 million cases averted is a low estimate, since the authors did not include other vaccine preventable diseases such as chickenpox, hepatitis B, smallpox (even though the vaccine was available over 200 years ago, and the disease is “extinct”, it was eliminated by vaccines), and other diseases. The number could be substantially higher.

Let’s review the data, just to make it easy to remember:

  1. The data was gathered from public reports that go back to 1888. There were hundreds of thousands of data points. (Editorial note: this is difficult, time-consuming work, a hallmark of good science–one hour of researching Google, typical of the vaccine deniers, does not science make).
  2. The researchers found that, in total, over 103 million cases of diseases were averted since the launch of vaccines for each of the vaccines.
  3. Over 2.36 million people avoided contracting these contagious diseases in 2010 alone as a result of vaccinations.
  4. Non-vaccine factors, such as hygiene and sanitation, had some effect on the variability of the rates of diseases prior to the launch of some vaccines, but it was only after the licensure of the particular vaccine that the rates dropped to near imperceptible levels with no (or minor) variability. 

To make this absolutely clear: Vaccines Prevent Diseases. Vaccines Save Lives. And we now have more evidence supporting these assertions–solid, hard-won, detailed, nearly irrefutable evidence.

Update. The French language blog, Rougeole Epidémiologie (in English, the Epidemiology of Measles), applied this data and analysis to France. Though my French reading skills are rudimentary, Julie Boulier (the author) reports that the estimated number of diseases that are prevented in the upcoming year by vaccines would be:

  • 780 000 cases of measles,
  • 350 000 cases of rubella,
  • 440 000 cases of mumps,
  • 120 000 cases of diphtheria,
  • 780 000 cases of whooping cough
  • and 4000 cases of polio

And in case it’s not been made clear in this blog over the past couple of years, each of those vaccine-preventable diseases can be and are dangerous to adults and children. Vaccines are saving lives in France, and Julie Boulier provided evidence to support that.

If you need to search for scientific information and evidence about vaccines try the Science-based Vaccine Search Engine.


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Michael Simpson

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