Statistical Risk of Suffering a Severe Case of Vaccine-Preventable Disease
All of the below is from “
The Vaccine Book
Now that I’ve told you the possible risks of a vaccine reaction, what about the statistical chance that your child might get a severe, life-threatening case of one of these diseases? To my knowledge, that information has never been determined accurately through precise scientific statistical analysis…
We have good data on the total number of cases of most diseases, as well as the total number of fatalities. But what we don’t know is how often a severe case results in hospitalization or disability but not death. However, we can make some educated assumptions about most of the diseases based on what we know about each illness and the percent chance each illness usually causes problems…
In order to be classified as serious, a disease has to require hospitalization, cause permanent disability, or be fatal… Most of these numbers are fairly accurate based on what we know about each illness and data collected by the MMWR (the official CDC disease-reporting system). In some cases, where accurate data don’t exist, I’ve had to make an educated guess.
- HIB — 25 hospitalizations
- Pc — 10,000 hospitalizations (very approximate)
- Diptheria — 5 hospitalizations (yearly maximum; some years there are 0)
- Tetanus — 5 hospitalizations
- Pertussis — 1500 hospitalizations (very approximate)
- Hepatitis B — 130 cases, all severe
- Rotavirus — 50,000 hospitalizations (approximate)
- Polio — 0
- Measles — close to 0
- Mumps — 10 hospitalizations (approximate)
- Rubella — 3 babies born with defects
- Chickenpox — 200 hospitalizations (approximate)
- Hepatitis A — 20 hospitalizations (approximate)
- Flu — 20,000 hospitalizations (approximate)
- Meningococcal disease — 2750 hospitalizations
- HPV — close to 0 until sexual activity begins
This list gives us a very rough total of about 85,000 severe disease cases each year in children. We know that the current U.S. population of kids twelve and under is about 50 million. Dividing 50 million by 85,000 cases means that each child has a 1 in 600 chance of suffering a severe case of a vaccine — preventable illness over the first twelve years of life.
But this isn’t a very accurate way to look at disease risk for children. The various diseases affect children in so many different ways at different ages. Some infant diseases occur mainly during the first two years of life and are virtually unheard of beyond that. Some diseases are serious only during the first year of life but are fairly mild when they occur during childhood. Other diseases are mild during young childhood but more severe later on. So it isn’t very useful to think of all these diseases in our entire childhood population as a whole.
The most accurate way to assess the risk of having a severe case of a disease is to follow one group of infants throughout their entire childhood and to discuss each disease as it tends to occur at the various ages. Dr. Sears then proceeds to make educated estimations, of which the estimations are below:
The first six diseases below are responsible for the vast majority of serious infant disease cases. The disease risks are mainly worrisome for the first two years or so. For the rest of childhood and into the adult years, these disease have a much lower risk of being serious.
- HIB (meningitis, bloodstream infection). During the first two years of these 5 million (the number of babies born each year in the United States) babies’ lives, the risk of a severe case of HIB is about 1 in 200,000 (5 million divided by 25 cases). Beyond age two, the risk is close to 0.
- Pc (meningitis, bloodstream infection). This is similar to HIB in that it mainly occurs in the first two years. The disease risk would therefore be about 1 in 500 (5 million divided by 10,000)
- Pertussis (whooping cough). With about 1500 severe cases each year in infants (virtually all fatalities and hospitalizations occur in the first six months of life), the severe disease risk would be about 1 in 3333. This risk really applies to the first year of life.
- Rotavirus (diarrhea / dehydration). Risk is estimated to be 1 in 100 of a severe case. It is rarely severe beyond age two.
- Flu. Severe disease risk is about 1 in 250 during the first two years, when the flu is most risky for kids. For older kids and young adults, flu hospitalizations are very rare. With only about 50 fatalities reported each year, I would estimate 2000 hospitalizations. This calculation gives us a disease risk of about 1 in 2500 for children and young adults.
- Meningococcal diesease (meningitis). Disease risk is about 1 in 2000 in infancy. Between then and preteen years, risk is about 1 in 20,000. The vaccine isn’t yet available for kids during childhood, so this risk is unavoidable for now. Only about another 250 cases occur each year during the teen and college years. So from age twelve, when the vaccine is currently given, the disease risk is only about 1 in 20,000.
The remaining ten diseases, which apply more to later childhood and adulthood:
- Hepatitis A (liver disease). According to the actual number of reported cases, we may expect about 130 cases of this disease in our group of 5 million kids over the first twelve years of life. That’s a disease risk of about 1 in 40,000. Among teens and college-age kids, when contracting hep B becomes a greater possibility, about 1300 cases are reported each year. This number puts the disease risk at about 1 in 4000… As stated on page 50, however, the true risk may be much higher.
- Chickenpox. Severe disease risk would be about 1 in 25,000. For teens and young adults, for whom chickenpox is more serious, we may see another estimated 200 serious cases yearly, with a similar risk.
- Tetanus. This disease is virtually unheard of in the first five years of life. Disease risk is about 1 in 50,000.
- Diptheria. This illness is so rare that I put the risk at close to 0 for all age groups.
- Measles, mumps, and rubella. Severe cases during childhood are so rare that this risk is close to 0. Just for argument’s sake, however, we can use the 20 hospitalizations during the 2006 mumps epidemic to give us a mumps disease risk of 1 in 250,000 for teens and young adults. We can also use the 3 known cases of babies born with rubella birth defects each year to establish a severe disease risk of about 1 in 1.6 million.
- Hepatitis A (temporary liver disease). Severe cases in children are extremely rare. In teens and young adults, we may see about 200 severe cases yearly, putting the risk for the older group at about 1 in 25,000.
- Polio. This disease doesn’t occur in our country, so the risk is 0 for all age groups.
- HPV (genital warts). Risk is 0 until sexual activity begins… If we consider the number of adult women who eventually have a serious case of HPV warts or cervical cancer, we can estimate about 20,000 cases each year. This calculation gives us a disease risk of about 1 in 250.
As you can see, the risks vary greatly when we compare serious infant diseases with the rest of the childhood ones…
Now, as we watch our 5 million kids grow up, how do we weigh the severe disease risk against the risk that they will suffer a severe reaction to a vaccine? I told you previously that I don’t know how many severe reactions have occurred with each of these vaccines individually…. the VAERS database (the Centers for Disease Control’s Vaccine Adverse Events Reporting System, or “VAERS”) may have the information we need to understand the exact risk of reactions to individual vaccines but these data aren’t accessible. We know that some vaccines cause more severe reactions than others. Some have severe reaction rates that are much higher than 1 in 100,000, while others are lower. An older vaccine was taken off the market in the late 1990s (DTP; see page 35) because the risk of a severe reaction (seizures or sudden shock) was a frightening 1 in 1600 doses. It doesn’t seem that any of today’s vaccines have a risk even close to this ratio. I hope someday to make detailed information available to you. For now, all I can offer is the overall risk of a vaccine section.
… Dr. Sears then proceeds to provide stats on the estimated incidence of severe cases of a disease over a lifetime in our population as a whole. This estimates to approximately 200,000 serious cases of vaccine-preventable diseases each year. We have about 300 million people in the United States. So each person in this country has a 1 in 1500 chance of suffering a severe case of a vaccine-preventable disease each year (300 million divided by 200,000).
In summary:
- The risk of a reaction from a single vaccine seems to be about 1 in 100,000. The risk that any one child will suffer a severe reaction over the entire twelve-year vaccine schedule is about 1 in 2600.
- The risk of any one person suffering a severe case of a vaccine-preventable disease each year in our entire population is about 1 in 1500.
- The risk of a child having a severe case of a vaccine-preventable disease is about 1 in 600 each year for all childhood diseases grouped together. This risk varies widely depending on the disease. Some disease risks are close to 0. Infant diseases are more risky than childhood ones.
- We don’t know the exact number of serious vaccine reactions, as many are likely to go unreported or are not recognized. We also don’t know how to factor in possible long-term, hidden effects of vaccines. If we someday can learn these numbers, the known vaccine risk may increase.
So we come back to our original question: Are vaccines safe? Yes. Do they have severe side effects? yes. Are these severe side effects common? Not very. Is vaccinating to protect against all these diseases worth the risk of side effects? That’s the million-dollar question.
