What Causes Autism?
Why Can't We Get Rid of Disease?
Pollution May Be Linked to Autism
In December, a measles outbreak began at Disneyland and, according to some reports, now involves upwards of 77 cases. It's the latest major outbreak to draw attention to a growing trend in the U.S.: more and more families are opting to not vaccinate their children. The Disneyland case shows both the benefits of vaccination as well as the consequences of forgoing them.
First, some background on how the measles vaccine works. Like most vaccines, it administers a slightly altered version of a live virus. As the virus replicates, the immune system produces antibodies to fight against it. The measles vaccine is typically given in two doses that are 97% effective at preventing infection. Although the vaccine has a good success rate, measles is an extremely contagious virus that can thrive in a densely populated place like Disneyland.
Even some people who get vaccinated can be susceptible to measles-sources estimate this number is usually around 3% of recipients. These people do not usually get a full version of the virus though. Since they have at least some built-up immunity, symptoms tend to manifest as a rash or something minor. In addition, vaccinated people who contract the virus are far less likely to transmit the virus to another person.
This highlights a crucial point about vaccinations in general-herd immunity. Vaccinations are most effective when as many people get them as possible. When a community turns out in large numbers to get vaccinated, the treatment is more effective and everyone benefits, including those who opt out. In the U.S., about 92% of the population is vaccinated or immune and that makes it difficult for one case of measles to spread.
Outbreaks like the one at Disneyland could become more common as more families are choosing to forgo vaccinations, including the one for measles, mumps, and rubella. Although it has since been discredited and entirely rejected by the scientific community, a 1998 study suggested there was a link between autism and vaccinations. Still, some parents believe there is a causal relationship. Others fear too many vaccinations can harm a child's overall immune system.
Ultimately, there simply may be a communication gap when it comes to credible vaccination information. Last year in Ohio, there was a sizeable measles outbreak among the Amish community there. Medical professionals approached the community elders with information on vaccines and that seemed to do the trick, according to Dr. Robert Frenck, director of infections disease at Cincinnati Children's Hospital. He told The Wall Street Journal, "When the Ohio Department of Health went in and talked to their elders, they said we really don't have an objection to the vaccination. We just didn't understand it was that important."
How Well Do Vaccines Work? (via U.S. Department of Health and Human Services)
"Vaccines work really well. Of course, no medicine is perfect but most childhood vaccines produce immunity about 90 - 100% of the time."
State Vaccination Requirements (via the Centers for Disease Control and Prevention)
"No federal vaccination laws exist, but all 50 states require certain vaccinations for children entering public schools. Depending on the state, children must be vaccinated against some or all of the following diseases: mumps, measles, rubella, diphtheria, pertussis, tetanus, and polio."
What Is "Herd Immunity"? (via PBS)
"Just as a herd of cattle or sheep uses sheer numbers to protect its members from predators, herd immunity protects a community from infectious diseases by virtue of the sheer numbers of people immune to such diseases."
Lancet Retracts 'Utterly False' MMR Paper (via The Guardian)