Getting a grip on the risks of vaccination

By Brian Rotenberg

A version of this commentary appeared in the Toronto Star, the Medical Post and the Winnipeg Sun

ROTENBERG_Getting a grip on the risks of vaccinationsEvery day when I see patients in my surgical clinic, some are offered a procedure to help them feel better. Whether it is a minor surgery like a tonsillectomy, or something larger scale such as tumor resection, I have a full discussion with the patient regarding the benefits and risks of doing “something.”  Each time I go over the common minor risks of an intervention and the exceedingly rare, but potentially very serious risks that can occur.  I also review with them the risks of doing “nothing” – of what may happen if they don’t have surgery.

Vaccination is no different.  Vaccination involves an injection in order to provoke the body’s immune response to protect against an outside infection.  Like all medical therapies, vaccination has both its benefits and its relative risks, and an informed patient or parent needs to balance the two.

In the case of the Measles Mumps Rubella vaccination (also known as MMR), its overwhelming success in eradicating deadly diseases of childhood speaks clearly to the benefits.  However, it has become fashionable in society recently to hold vaccination to a different standard than most other medical risks individuals generally accept when they receive healthcare.

Understanding the nature of relative risk can help to frame the issue into a clearer perspective.  Not all risks are the same either in terms of likelihood or severity, and sometimes the risk of doing nothing can be potentially more harmful than the risk of doing something.

In the case of MMR vaccination, the risks of doing something – of receiving a vaccine – include relatively common but minor issues such as fever or a sore arm, and an exceedingly rare severe allergic reaction called anaphylaxis.

The risk of doing nothing – of not receiving a vaccine – at first glance seems very simple, that being a higher likelihood of getting the disease the vaccine is designed to prevent.  In the case of measles for example, the risk of getting the disease if an unvaccinated person is exposed to someone carrying the virus is very high, close to 100%.  People who have measles then subsequently have the further risk of developing a host of devastating medical problems including brain damage, deafness or blindness.

However, there is a more serious but hidden risk of doing nothing — not getting the MMR vaccine — that being the risk of causing serious harm to someone else who hasn’t received the vaccine.  Not all people can be vaccinated even if they wanted to be (e.g., very young children and people having chemotherapy) and because of this, they are at higher risk for catching a contagious disease.  Measles is one of the most contagious diseases known.

In order to have a low likelihood of transmitting measles to those who are unable to be immunized, it is estimated that approximately 95% of the population has to be vaccinated.  According to the Public Health Agency of Canada, the overall country-wide MMR vaccination rate just barely meets that mark (based on the most recently available 2011 data).  If the vaccination rate begins to fall in different provinces, our population will lose its overall immunity.

The media are reporting daily new outbreaks of measles in children in Canada and the United States, a scourge society once thought defeated.  There appears to be a strong cause-and-effect relationship between the emerging trend not to get vaccinated and the growing number of new sick children.

The overwhelming majority of cases of measles are in children who did not get vaccinated.  This fact should not be seen as surprising.  For those children, the parents’ decision to do nothing is what allowed the virus to grow within them; in their case, the decision to do nothing clearly outweighed the risk of doing something, with potentially life-altering consequences.

Even these small dips in vaccination rate have had major consequences – just imagine if the trend continues?

Patients who are considering not getting an MMR vaccination for themselves or their children need to compare the relative risks of doing something versus nothing.  In the case of the MMR vaccine, doing nothing is the more dangerous choice — and it is putting children, and society at large, at risk.

Dr. Brian Rotenberg is an advisor with EvidenceNetwork.ca and an Associate Professor in the Department of Otolaryngology – Head & Neck Surgery at Western University, London, Ontario.

February 2015

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