By DR. RICHARD RUPP AND BRIDGET HAWKINS
Dear VaccineSmarts,
My friend Kathy keeps sending me anti-vaccine articles. The last was about a baby that developed cradle cap after receiving vaccines. Kathy’s trying to persuade me to stop vaccinating my 5-month old, but I plan to continue vaccinating my son. Is there something I can say to convince her that vaccination is not the root of every problem?
Kelly — Galveston
Dear Kelly,
Thank you for sending the article which illustrates how many with anti-vaccine sentiments do not understand the difference between correlation and causation. Reviewing these concepts may help your friend.
Everyone should agree with the following statement: just because someone is vaccinated, does not mean that bad things will never happen to him or her.
At any time bad things can happen that are not related to vaccination. This is what anti-vaccine groups frequently miss. The mother in the article attributes her child’s cradle cap to the vaccines and doesn’t consider any other cause. In reality, cradle cap is a common condition at two months of age, which is when the first set of vaccines is given. Exposure to the high levels of hormones during pregnancy causes this skin condition, which is self-limited and resolved as hormone levels drop in the months following birth. The mother says her child’s cradle cap ended because she refused additional vaccines, but it would have been resolved anyway.
A common example used to teach students about correlation and causation, is ice cream and shark attacks. Ice cream consumption jumps in the month of May, steadily rising throughout the summer and then falls off in September and October. Shark attacks follow an almost identical track. There is a high degree of correlation between ice cream consumption and shark attacks.
Following the reasoning of many in the anti-vaccination groups, this tight correlation indicates that ice cream is causing shark attacks. Perhaps, sharks are angry that they are not getting their share of the ice cream?
Of course, most people will see that one is not causing the other. The connection between the ice cream and shark attacks is the temperature outside. People eat more ice cream and swim in the ocean because it is warmer during the summer.
Sometimes the connection between two correlated events is not obvious. Prior to vaccines being approved, clinical trials are conducted that note any negative outcomes or side effects such as fever, soreness and whether they are caused by vaccines.
Occasionally, concerns arise after a vaccine is licensed. These concerns are carefully studied to determine the cause. The risks related to current vaccines are well-studied and described. Vaccination is only recommended when the benefits far outweigh the real risks.
Dr. Richard Rupp is a pediatrician and professor and Bridget Hawkins, Ph.D., is an assistant professor at UTMB. Visit our blog at http://blogs.utmb.edu/vaccinesmarts/ or like us on Facebook or follow us on Twitter @VaccineSmarts.