This 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 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 ninety-five 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 particularly vulnerable because they cannot make healthcare decisions for themselves, but instead rely on the judgment of their parents, and at the same time are particularly susceptible to communicable diseases. Parents do, in fact, have the right and responsibility to make decisions for their children, so the interest of an individual child is often not enough to compel vaccination. However, allowing the vaccination rate to fall below the levels required for herd immunity puts those who cannot be vaccinated for medical reasons at increased risk. Again using measles as an example, there is considerable overlap between those who cannot receive the vaccination and those who are most at risk of measles complications (specifically infants less than twelve months old, pregnant women, and people with compromised immune systems due to cancer, AIDS, or immunosuppressant drugs). In passing this vaccine legislation, California gives the public interest priority over individual rights, and the Courts have given indications that they will uphold the law in the face of First Amendment challenges.
Meanwhile, in Canada…
Ontario is one of only two provinces that make childhood vaccinations mandatory for children entering school, but exemptions for philosophical reasons can be obtained by filling out a form. Otherwise there is a fine for up to $1000. So far there is no indication that any government in Canada is seeking legislative measures to increase childhood vaccination rates. With measles vaccination rates below fifty percent in some Toronto schools, it may only be a matter of time before an outbreak turns into an outcry.
One final note on the flu vaccine
I know, no one wants a reminder that winter is coming, but it’s time for a friendly public service reminder. Influenza is a rapidly changing virus, which necessitates generating a new vaccine every year. There are multiple strains and it is difficult to predict which strain may be most prevalent in any given year, so the efficacy varies but is generally lower than other vaccines. Even with lower efficacy, a high rate of vaccination will still decrease transmission, which ultimately helps to protect those most vulnerable to complications such as infants and the elderly. So show your grandma and infant niece that you love them—go get your flu shot!