In the last few years, the rates of vaccine-preventable illnesses have been on the rise. And this isn't just something that's been happening in the United States; it's happening throughout the world. Often, these outbreaks begin with unvaccinated people. They spread through them, too. Outbreaks occur because of a breakdown in herd immunity -- that's the topic of this week's Healthcare Triage.

   Here in the United States, vaccines are often required in order for kids to attend school. The government does however respect the rights of individuals to refuse vaccinations for themselves or their children for religious and even sometimes principle reasons. Sure, they make them jump through hoops in order to get these exemptions, but they do occur. When people don't get vaccinated though, that can lead to a breakdown and what we call herd immunity.

   Before we get to that though, we need to review some basic facts about vaccines. The first is that they aren't perfect. While they do significantly decrease your chance of getting a disease if you come in contact with it, there's still a risk that you could get sick. Vaccine success as a public policy depends not only on the added protection that vaccines confer upon those who get shots, but also on the decreased likelihood that anyone's going to come into contact with the disease: that's what's known as herd immunity. Once enough people are immunized, then there really can't be an outbreak. If enough people aren't immunized and someone gets sick, the disease can then spread. More people get it, more and more people are exposed, and that's how you get an outbreak. That's bad. But if lots of people are immunized, then even if someone gets sick, the likelihood of anyone else getting sick and spreading the disease is really low. That's good. And if there can't be an outbreak, then everyone is protected, even those who can't get vaccinated. This is critical, because there are people who are at increased risk for communicable diseases but they can't be given shots for various reasons. Small babies, for instance, are susceptible to certain diseases but they can't be given all vaccines. The elderly can have potentially impaired immune systems and be at higher risks for diseases, and the same goes for all immunal-compromised patients who are always under the thread of infection.

   We get so caught up in the discussion about how vaccines protect those who get them that we sometimes fail to focus on the other important reason immunizations are important: they allow us to protect those who cannot protect themselves. To the research!

   In 1995, the varicella vaccine, or the chicken pox vaccine, was introduced in the United States, and overtime more and more children were vaccinated. In 2011, a study was published in the journal Pediatrics that looked at how the program had affected the number of kids who died from the disease each year. The first thing the paper noted was the deaths from varicella went down significantly from before the vaccine was released to six years later. Then from 2001 through 2007, the rates of death remained much lower with just a few dozen children dying nationally from varicella each year. What's really amazing though is that from 2004 through 2007, not one kid less than one year of age died in the United States from varicella. None. This is remarkable because we can't give the varicella vaccine to babies. It's only approved for children one year of age or older. In other words, all of those really young kids were saved not because we vaccinated them against the illness, they were saved because the other children were. Enough older kids were vaccinated to grant herd immunity to protect the babies from getting sick.

   Wide spread vaccination prevents outbreaks from occurring. It protects all people from getting ill, and when parents refuse vaccines for their children, they leave us at increased risk. In order to combat this threat for the last few years, some schools in New York City have been refusing to allow unvaccinated children to attend school when outbreaks occur, sometimes for weeks or more. Some parents thought that this was unfair and filed lawsuits. Just recently though federal court ruled that schools have this power. The court cited the government's right to make such decisions to protect public health. Parents want to allow their kids to remain at risk by leaving them unimmunized and they get sick, the state has to take steps to prevent outbreaks from occurring. In New York, one of the few children who developed measles earlier this year was an unvaccinated child. The state refused to allow that child's sibling who was also unvaccinated to go to school. That child also developed measles. The school maintains -- and it's hard to dispute -- that allowing that child to go to school would have put everyone at higher risk.

   People who refuse to vaccinate themselves or their children aren't just putting themselves at risk; they're putting everyone else in danger, too. American courts have held, once again, while they may have the right to the former, they don't always have a right to the latter.