special report
12 Obiter Dicta
Declining Vaccination Rates
andrea uetrecht › contributor
T
his past summer, California
passed a bill narrowing the scope
of allowable vaccine exemptions
for children entering public
schools, private schools, and daycares.
Personal and religious exemptions
have been eliminated; only medical
exemptions remain. This seemingly
heavy-handed legislation is intended to
increase the childhood vaccination rate,
which has been declining over the past
decades.
Why vaccinate?
Vaccination is arguably the easiest and most effective
tool to control and potentially eliminate infectious
diseases. The combination of an effective vaccine
and an aggressive vaccination campaign was the key
to eradicating smallpox in 1979. The risks associated
with most vaccines are very small, while the diseases
themselves can be debilitating and sometimes fatal.
Take measles for example. According to information
available from the Centers for Disease Control and
Prevention (CDC) the symptoms and complications
of measles (and their frequency) are: fever (greater
than forty degrees Celsius) and rash (most people),
acute encephalitis and brain damage (while often
permanent, only occurs in one in one thousand of
cases), and death from respiratory or neurological
complications (one or two in one thousand). The
ê Photo credit: Nikolai Litov via Shutterstock
ê Photo credit: Fox News
measles vaccine is ninety-five to ninety-seven percent
effective in preventing measles, and has the following
side effects: mild fever (one in six), mild rash (one
in twenty), fever-associated seizure (one in three
thousand), and life–threatening allergic reactions
(less than one in a million). Comparing the two, it’s
clear to see why vaccination makes sense. So why have
vaccination rates in North America been declining
over the past several decades?
Fabricated Data, Celebrities, and a Fearful
and Distrustful Public.
The decline in vaccine rates in North America began
with a 1998 publication by British former surgeon
Andrew Wakefield, claiming a link between vaccines
and autism. Researchers have since been unable to
verify his findings, and while we are still unsure as
to the cause(s) of autism, extensive data make it very
clear that vaccines are not a causative agent. Many
allegations of misconduct leveled at Wakefield led
to findings of dishonesty, deliberate falsification of
research, and abuse of developmentally challenged
children. This ultimately resulted in the retraction of
his publication from The Lancet, and his removal from
the UK medical register. This was not before celebrity
Jenny McCarthy took up the charge. Believing that her
son’s autism was caused by vaccination, she has been
on a crusade to warn parents about what she believes
to be the dangers of vaccines. Her campaign has
worked. Other celebrities from Jim Carrey to Charlie
Sheen have spoken out against vaccines, and Donald
Trump has recently brought the issue to the center of
the political arena. The views of these celebrities strike
a chord with some parents who may be fearful of doing
something that might injure their child. Further,
many people are also distrustful of both government
and pharmaceutical companies. To be sure, as with
any company whose primary responsibility is to their
shareholders, pharmaceutical companies have acted
poorly from time to time. When this happens they
are inevitably found out and held accountable to the
public (Volkswagen anyone?). Some of the concern
surrounding vaccine safety was that the use of a
mercury-containing preservative called Thimerosal
in vaccines administered to children might interfere
with cognitive development. However, while
Thimerosal was removed from childhood vaccines in
Canada by 1998 and in the US in 2001, autism rates
have remained steady. Combine these factors with a
collective amnesia of what it was like when measles
and other vaccine-preventable diseases ran rampant,
and people start to think twice about vaccinating.
Finally, psychological research suggests that doing
something that has the possibility of negative
consequences is more unpleasant that not doing
something to prevent negative consequences, and
this may be another factor contributing to the decline
in vaccination rates. This decline was linked to the
measles outbreak at Disneyland earlier this year.
Herd Immunity
From a public health standpoint it is important that
as many people as possible are vaccinated to establish
something called “herd immunity.” What this
effectively means is that a high enough proportion of
the population is immune to the disease that it is very
unlikely that an isolated case of the disease will be
able to spread to a second person, let alone contribute
to an outbreak. The proportion of the population that
needs to be vaccinated for this to occur depends on a
number of factors, particularly the effectiveness of the
vaccine and the specific characteristics of the disease.
In the case of measles, although the vaccine is ninetyfive to ninety-seven percent effective, measles is so
contagious that nine out of ten unimmunized people
who come into contact with an infected person will
contract the disease; so more than ninety-five percent
of the population needs to be vaccinated to achieve
herd immunity.
Why make vaccinations mandatory?
Governments in Canada and the United States have
been hesitant to infringe on the rights and freedoms
of citizens, particularly related to health decisions,
and for good reason. However, governments also have
the responsibility to protect those most vulnerable
in the population, in this case children and people
who are unable to receive vaccinations. Children are
» see vaccines, page 23