The tests came fast and furious.  The diagnosis didn’t.

One doctor was certain it was psychosomatic.  My twin younger brothers had been born a few months earlier, and I, seeking attention, was refusing to walk.  My mother kept looking.

Another doctor couldn’t figure it out but gave a piece of advice.  “You have other children, right?  Be grateful. Take this one home, keep him comfortable, and when he is gone take comfort in the others.”  She ran out of that office (in tears, I imagine).

Eventually, a doctor found the answer.  I had an autoimmune disease called dermatomyositis.  My body’s immune system was attacking my muscles and leaving me weakened.  The disease normally affects older women, but in rare cases will strike children.  How rare is it? 2-3 cases per million children in the United States.  The cause was unknown, but some of the doctors guessed that it had something to do with an immunization I had right before the symptoms started.  My parents were cautioned against further vaccines.

The doctors put me on prednisone (a steroid that blocks the immune system), and I began the long, hard road back to walking, running, fighting with my brothers and becoming a ‘normal’ child again.  As years passed I learned to play tennis (not well, but passably), ride a bike (rode from Boston to New York for a fundraiser) … and live a normal life.

I saw a lot of doctors in my childhood.  A lot. Surgeons, neurologists, rheumatologists.

Some probably shouldn’t have been doctors. (At eight years old, I learned swear words from my older brother and used them on a surgeon. My mother didn’t discipline me. Years later she told me why. “You were right,” she said.).

But some of the doctors were great.  They made a really scary time less scary.  They were honest and told me when something would hurt and what they could do to help me.  They inspired me to do what they were doing.  From about six years old on, I wanted to be a doctor.

The year before I went to medical school, I worked in an urgent care center.  I needed to be vaccinated against anything I hadn’t been vaccinated against as a child.  I went to my mother for my shot record and heard, again, that vaccines had caused my childhood illness.  She reminded me that we had been warned I shouldn’t get any more immunizations.

So I took my records to an immunologist to consult on what I should do.  He went through my records, reviewed the current literature and came up with a remarkable conclusion.  First, because of advancements in science we knew my illness was unlikely to have been caused by vaccines.  Second, I hadn’t had a vaccine reaction.  You see, I hadn’t had a vaccine for six months before the disease struck.

This was stunning to me.  Doctors had said, I had thought, my family had known, for years that vaccines caused my disease.  We all knew what had happened. I was a normal child who had gone to his pediatrician and, shortly thereafter, been struck with a disease related to my immune system.  We blamed vaccines for years of fear and pain and the loss of many childhood experiences. And it wasn’t true.

After this revelation, I completed my recommended vaccine series with an MMR, polio and DTP.  I also was vaccinated against hepatitis A and hepatitis B.  The only consequences I suffered were sore shoulders.  Since then I have had tetanus and pertussis boosters as well as my annual flu shot.

I have told this story to many families who tell me their children won’t be vaccinated because a friend, a cousin, an acquaintance told them about their child who died or developed a horrible illness “right after she got her shots.”

This interpretation is not a malicious one. People didn’t set out to blame vaccines. It is the intersection of two phenomena.

First, much of the first two years of life is “right after vaccines.”  Kids at this age are doing all sorts of wonderful things … first words, first steps, developing personalities.  And when we think of something that was wrong, that made them cry we will often remember the days we left the doctor’s office with a crying child who had been “stuck.”  Statistically speaking, most maladies that afflict children in the first two years will be right after a shot.

Second, many of the horrible diagnoses that happen to children in the first two years of life are without reason. With few exceptions, we can’t say that their diet gave them diabetes or that smoking gave them lung cancer, like we can with adults.  So if I have to come into the exam room and give bad news, I often don’t know why this child is sick while another one isn’t.  I used to tell my patients that we may never know why, but today, with the advancing of genetics, we are finding that more and more of these diseases are caused by tiny flaws in the human genome, flaws we are only just discovering and are still years from treating.

I hope my story, of why I went to medical school and why it was not the vaccines that made me sick, will help a scared new parent (and what new parent isn’t worried about the new life they are responsible for?) make the decision to vaccinate their child.  As a father, I make sure my son gets all his shots on schedule, for his benefit and the health of all the people around him.  Rather than avoiding vaccines because of family stories and urban legends, they can be given to prevent diseases that definitely exist and definitely can make our children desperately ill.

Andrew Cronyn is a pediatrician who blogs at Parents for Vaccinations.