Sensible decision-making about vaccinations
Should you vaccinate your children or not? That's the common
question, but it's not the right question. Every disease is
different, and if you are thinking about whether to vaccinate you
should inform yourself about the risks of each disease and of each
vaccine and make your decisions independently.
The standard scenario
When a serious disease is common, everyone wants to vaccinate. While
there might be some danger to the vaccination, the danger of the
disease is more serious and very clear. But when the vaccination
program is successful and the disease becomes rare, then people worry
that the risks of the vaccination are worse than the risks of the
disease, and some people stop vaccinating.
There are really two versions of this idea. In one case, the parents
think that no one should be vaccinating, because the vaccination has
eradicated the disease. In the other, the parents feel that, given
that most other people are vaccinating, the risks to their own child
are less by not vaccinating. In the rest of this document I will
discuss only the facts of the situation, and only mention briefly here
that this choice puts you in the morally questionable position of
being a "free rider": you profit from the risks that others are taking
and that you are not willing to take yourself.
To make a sensible decision about whether to give your child a
specific vaccine you have to understand the dangers of the disease and
the dangers of the vaccine. The risks due to the disease are of
course first the risk of catching it and then the seriousness of the
disease when you have it. It's important to guard against the belief
that your children have no chance of getting a disease merely because
its incidence of has been reduced by vaccination and it is no longer
The risks of a vaccine are harder to determine than the risks of a
disease. Children are vaccinated and then a tiny number of them
develop some problem. Is the problem caused by the vaccination? It's
hard to tell, because unvaccinated children also develop problems.
Only a very careful study of the incidence of a specific problem in
unvaccinated children will determine cause and effect. Anecdotal
evidence will be of no use here.
Because you are weighing one risk against another, it's important to
think clearly. Don't let emotional reactions to diseases or vaccine
reactions overwhelm your ability to weigh the odds. If one vaccinated
child in a million has gotten a severe reaction, while one
unvaccinated child in ten thousand has gotten a serious disease, you
probably should vaccinate, even if the one child in a million was your
own. You have to really find out the statistics, because what you
hear about is often distorted by various biases. For example, many
people think that driving is safer than flying, whereas it's quite the
other way around. Presumably the reason for the misconception is that
plane crashes often kill many people at once and so they are more
newsworthy than the steady and much larger loss of life in
Here are some notes on some specific diseases against which
vaccinations are available.
Polio in the United States fits the standard scenario quite well. The
disease has been eradicated worldwide except for a few isolated areas.
The chance that your unvaccinated child will get polio is very small,
and one might argue that the disease is so well contained that even if
no one in the States vaccinated it would still be OK. Because of this
situation, standard practice in the U.S. is no longer to give the oral
polio vaccine (OPV), which had a nontrivial incidence of serious side
effects. Instead there is an inactivated vaccine (IPV) which as far
as we know is free of side effects.
Hepatitis B is primarily transmitted sexually or from mother to child
at birth, although there is apparently some risk of transmission in
other sorts of close contact. If the mother is infected with
Hepatitis B than the child should be vaccinated immediately after
birth and also get immune globulin (antibodies). If the mother is
not infected, it would seem unnecessary to vaccinate the child before
the teenage years. Unfortunately, it is unusual to test the mother, and
instead children are routinely vaccinated at birth and in infancy.
The situation with tetanus is utterly unlike the standard scenario.
Tetanus isn't spread from person to person, so it makes no
difference if other people vaccinate. Instead one gets it from
bacteria that live in the ground. Since humans are not the primary
host, the disease will never be eradicated. If you don't vaccinate
your child against tetanus you risk a serious disease.
Pertussis (whooping cough) is a serious disease that is controlled by
vaccinations but is nowhere near being eradicated. In fact, whenever
people stop vaccinating against pertussis it comes back. Even if you
are willing to be a free rider, your child still has a significant chance
of being exposed.
The idea of not vaccinating against chickenpox (varicella) is
completely different. Here people think that the disease is mild in
children and they will deliberately expose their child, essentially
using the disease itself as the vaccine. It is certainly correct
that having had chickenpox is completely protective against getting a
new case, whereas the long-term efficacy of the vaccine is not known.
Even in the short term, it is not completely effective.
But there are two problems with deliberately exposing your child to
chickenpox. One is that is not always such a mild disease. In fact
about 1 child in 100,000 who gets chickenpox will die of it. Of
course that is a small number, but it is still much higher than the
number of people dying from the vaccine, which is no more than 1 in
The other problem is that having had chickenpox puts you at risk for
getting shingles later in life. Shingles is very unpleasant, and the
chance of getting it from the chickenpox vaccine is much lower than
if one has had the disease.
Specific vaccine risks
A lot of misinformation is being passed around about vaccine risks.
Part of the problem is that people whose children become sick or die
shortly after being vaccinated to tend to blame the vaccinations, even
if there is no causal connection. Here are some specific issues that
one often hears about.
Thimerosal is a mercury based preservative used in some vaccines.
Some concern has arisen over harmful side effects due to mercury in
injections, and as a result this preservative has been mostly
eliminated. The only childhood vaccines that still contained
thimerosal in 2003 are for influenza and tetanus/diphtheria, but not
the much more commonly given tetanus/diphtheria/pertussis vaccine.
Thus if you're concerned about mercury, the only vaccination to avoid
One sometimes hears that vaccines contain "tissue from aborted
fetuses", which is not true. No tissue that came from any fetus is in
the vaccine. What is true is that some cell cultures were established
decades ago using cells from aborted fetuses, and that viruses for
vaccinations are grown in those cell cultures. But no cell that came
from a fetus is part of the vaccine, and no abortions are performed as
part of the process of vaccine production.
Autism and SIDS
Some concerns have been raised that vaccinations lead to SIDS or to
autism. Several carefully done studies, however, have found no such
link in either case.
What we did
We have vaccinated our twins according to pretty much the standard
American recommendations. We didn't find out about the Hepatitis B
situation in time for the mother to be tested, so we had the newborn
vaccination, and then thought it was better to continue with the
regular schedule. We would not have given our children the oral polio
vaccine, but that was no longer recommended by the time that they were
Some closing words
If you don't want to decide for yourself about vaccinations, just do
what your doctor recommends. If you do want to decide for yourself,
then actually think about it for yourself. Inform yourself about the
diseases and the vaccines and make a reasoned decision. Don't just go
along with what you heard somewhere or what someone else is doing.
A few links
Here are a few links from the Centers for Disease Control: