There’s Value in Vaccines, Even When Not 100% Effective
Mar 02, 2012

Does the fact that vaccines are not 100% effective mean that they have no value in preventing disease?
Certainly not.
When we are vaccinated, we expect that the shot we receive will prevent us from acquiring certain diseases. After all, vaccinations are injections intended to stimulate the immune system so that it is able to recognize invading bacteria and viruses and produce antibodies to destroy or disable them, thereby preventing disease.  While this is certainly the intent of the vaccination, it is not always the result.
The unfortunate reality is that not every person will generate a protective immune response to a particular vaccine on a given day.  Chalk it up as a scientific limitation of modern-day medicine, but the truth is that vaccines are not 100% effective.
A person could produce an immune response to one vaccine, but not another. Or they could respond well to a vaccine on one day and not another. In fact, some people may never generate a protective response to a specific vaccine no matter how many times they receive it. And since we don’t always know why this happens, we can’t predict exactly when it will happen either. That is why we must accept that just because we are vaccinated doesn’t ensure that we are completely protected.
Fortunately, science does provide a way for us to test whether a person has generated an appropriate response to a vaccine by way of a blood test that is refered to as an antibody titer.  The National Institute of Health defines the antibody titer and explains that it is used to determine:

• The strength of an immune response to the body’s own tissue in diseases such as systemic lupus erythematosus (SLE) and other autoimmune disorders
• Your need for a booster immunization
• Whether a recent vaccine caused a strong enough response from your immune system to protect you against the specific disease
• Whether you have, or recently had, an infection such as mononucleosis or viral hepatitis

The fact that vaccines are not 100% effective actually helps explain why the vaccinated population should remain concerned about the number of non-vaccinated people there are within a community. The number of people immune to a specific disease versus those who are not immune can directly impact the likelihood of disease transmission.  
Certainly it is anticipated that most people will generate the expected immune response.  And even though some people may not have immunity because they are either (1) purposely unvaccinated, (2) too young or medically unable to be vaccinated, or (3) vaccinated but unable to elicit the proper immune response, The National Institute of Health explains they may still be protected through a concept called “community immunity”.

“When a critical portion of a community is immunized against a contagious disease, most members of the community are protected against that disease because there is little opportunity for an outbreak. Even those who are not eligible for certain vaccines—such as infants, pregnant women, or immunocompromised individuals—get some protection because the spread of contagious disease is contained. This is known as “community immunity.”

The concern comes when that “community immunity” is compromised by people who purposely go unvaccinated, which in turns compromises those who seek protection through vaccination.
The reality is that each disease has a different threshold of sorts – a point at which it is possible for the disease to reproduce and be transmitted within a community.  Different diseases require different coverage rates in order to stop the transmission of a disease and this coverage rate will depend on the reproduction number of the disease.
From this document provided by The World Health Organization, we understand that

“the coverage rate necessary to stop transmission will depend on the basic reproduction number (R0), defined as the average number of transmissions expected from a single primary case introduced into a totally susceptible population.Diseases with high R0 (e.g. measles) require higher coverage to attain herd protection than a disease with a lower R0 (e.g. rubella, polio and Hib).”

If we use a typical classroom of elementary school children as an example, we can understand that such a community may be at risk when as little as 5-10% of children do not possess immunity to a specific disease.  Whether their lack immunity is intentional or not really makes no difference once the disease begins to spread.  In these situations, even what may be considered a small percentage of  unprotected children can make conditions favorable for a disease outbreak in which even a vaccinated child may be at risk.  Perhaps this explains why some states are calling for tighter restrictions to vaccination exemptions.  They want to ensure that before a parent elects to exempt their child from vaccines, that they clearly understand the benefits that vaccination provides for the entire community and the risks they expose their child to by purposely choosing to forego vaccination.
The encouraging news is that we are beginning to see scientific advancements in today’s research that may one day help us to determine who may, or may not, respond well to vaccines.  And more importantly, we may begin to better understand why that is.  It’s really fascinating and the future promises great advancements in vaccine efficacy. However, this may only help those who elect to be vaccinated.  There is still much more to do to ensure that people make educated decisions about vaccinations and to do that we must continue to dispel common vaccination misconceptions such as those discussed on The History Of Vaccines blog:

• The “Overloaded Immune System” Misconception
• The “Disappeared Diseases” Misconception
• The “More Vaccinated Than Unvaccinated People Get Sick” Misconception
• The “Hygiene and Better Nutrition Are Responsible for the Reduction in Disease Rates, Not Vaccination” Misconception
• The “Natural Immunity Is Better Than Vaccine-acquired Immunity” Misconception

Even if vaccination is not 100% effective, vaccines are still effective in preventing the spread of disease and the subsequent suffering and death these diseases often cause.  Yes, vaccines may have limitations, but if we are able to maintain a high level of community immunity than we can keep diseases at bay.
Why not simply be a part of the community immunity rather than be a threat to it?  And why is it so difficult for the unvaccinated population to admit that that they are benefiting from the community immunity that their personal choices continue to threaten?

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