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All that really needs to be said about the measles outbreak: the vaccine is safe and it works

child getting vaccinated

As a website devoted to explaining complicated topics in healthcare, we haven’t really tackled the vaccination debate before, because, well… it’s not all that complicated. The science is clear: there’s no evidence that vaccines cause autism. End of story.

Or at least it should be. With so many people choosing to opt out of vaccinations, an outbreak of measles– a disease that the Centers for Disease control considers eliminated in the U.S.– recently infected at least 40 people at Disneyland who spread it to at least six states. In the midst of this, some prominent political leaders (most notably Rand Paul) have implied that vaccines actually do cause “profound mental disorders” despite zero credible evidence, while others, like New Jersey Governor Chris Christie, have said that the decision whether or not to get a vaccine is simply a matter of personal choice.

But while vaccines have gotten much more attention in recent weeks, there’s still not that much to say about the issue. According to Aaron Carroll, a professor of pediatrics at the University of Indiana who blogs at The Incidental Economist, all that really needs to be said on the subject are these points:

  1. Measles is a terribly infectious illness that is a public health issue.
  2. There’s a vaccine that is amazingly effective.
  3. The vaccine is very, very safe, and it doesn’t cause autism.
  4. Policies in the United States should try and encourage all children to get immunized, as we need almost everyone to be immune to achieve herd immunity.
  5. We should allow some people to forego vaccination if they absolutely must, but we should try to make sure it’s not for reasons that are scientifically wrong – ie violate (1), (2), or (3).
  6. Unvaccinated people can be restricted from certain public activities (ie school) during emergency situations like outbreaks.

We agree; however, we thought it might be helpful to explain the reasoning and scientific evidence behind each of them.  

1. Measles is a terribly infectious illness that is a public health issue.

Robert Cattaneo, a professor of biochemistry at the Mayo Clinic, says that unlike other respiratory viruses which live deep in the lungs, the measles virus hangs out in an infected person’s windpipe, where it’s in the perfect position to be sprayed when they cough. He tells Time magazine:

“The measles virus uses the trachea as a trampoline,” Cattaneo says. A single cough or sneeze will hurtle the measles virus through the air in enormous viral quantities, while other respiratory viruses have to travel further to get out. Once out of the host, the measles virus can linger on a surface for two hours, the CDC says. And if one person has it, 90% of the people nearby who aren’t immune will also become infected.

The symptoms for most people who come down with measles are just a rash and a fever, but in some cases it can be much more serious. In roughly, 1 in 1,000 cases the infection becomes systemic and moves to the brain, quickly causing behavioral changes, swelling, and convulsions, often leading to death or permanent disability, like blindness, deafness, or mental retardation. This is what killed children’s author Roald Dahl’s seven year-old daughter in 1962, the year before a vaccine was developed.

In about 1 in 5,000 measles cases brain damage develops years later. Alice Ackerman, chair of the pediatrics department at the University of Virginia, tells NPR:

“It doesn’t matter how bad your initial measles infection was. Up to about eight years later, children can start showing behavioral changes. They may have problems sleeping or start acting funny. It’s a degenerative process: The brain gets more and more physically damaged [from inflammation] over time.”

Those are rare cases though. Much more commonly, up to 1 in 20 people children with measles catch pneumonia– that’s what kills 145,000 children worldwide each year. So yes, measles is serious and very, very contagious.

2. There’s a vaccine that is amazingly effective.

A single dose of the measles vaccine is enough to provide immunity to 92% to 95% of people who receive it. In some people, the first shot doesn’t produce enough of an antibody response to protect them, which is why the CDC recommends two shots— that’s enough to provide protection for 97% of those who get vaccinated. (It also explains why so many adults are coming down with measles in the latest outbreak– they either weren’t vaccinated when they were children or they’re among the small percentage of people for whom it didn’t work.)

3. The vaccine is very, very safe, and it doesn’t cause autism.

Carroll, besides blogging at the Incidental Economist, also does a fantastic video series on YouTube called Healthcare Triage. In one episode, he laid out all of the research done on whether vaccines cause autism, and just one study– which was later retracted and repudiated by most of its co-authors– showed a link:

Later investigations showed that the lead author of that study, Andrew Wakefield, changed and misreported results in his research, to create the appearance of a link between vaccines and autism. For example, here’s what an investigation by England’s Sunday Times found:

In most of the 12 cases, the children’s ailments as described in The Lancet were different from their hospital and GP records. Although the research paper claimed that problems came on within days of the jab, in only one case did medical records suggest this was true, and in many of the cases medical concerns had been raised before the children were vaccinated.

4. Policies in the United States should try and encourage all children to get immunized, as we need almost everyone to be immune to achieve herd immunity.

Herd immunity is a situation where so many people are immune to a disease that the chances of a person who is not immune catching it is very slim. The measles vaccine may be incredibly effective, but measles is also incredibly contagious (if one person with measles entered a room full of unvaccinated people, 90% of them would get it). That means that a pretty high percentage of people need to be vaccinated to keep the disease from spreading– the CDC says that 92% to 95% of children should get two doses to control the disease. This will keep people who can’t get vaccinated for measles– either because they’re too young or because their immune systems are compromised– from getting sick.

One thing that’s gotten lost in all the recent measles vaccine hysteria is that for the most part we’re hitting those targets. A CDC report looking at found that nationally, a median rate of 94.7% of kindergarteners had been vaccinated in the 2013-2014 school year. The problem is that there’s a lot of variation by area. For example, that same CDC report found that vaccination levels ranged from 99.7% in Mississippi to 81.7% in Colorado; seven states and DC had vaccination rates lower than 90%.

At the community level, vaccination rates can be lower. In some schools in Los Angeles, 60% to 70% of parents filed “personal belief exemptions” stating that they’re not vaccinating their kids for various reasons– meaning these schools, in some of the wealthiest parts of L.A., have vaccination rates as low as Chad or South Sudan’s. (Actual vaccination rates– both on the community and national levels– might be a bit higher, because some parents get exemptions so their kids can enroll in school on time, but do get them vaccinated eventually.)

5. We should allow some people to forego vaccination if they absolutely must, but we should try to make sure it’s not for reasons that are scientifically wrong.

Carroll draws a distinction between those who avoid vaccines for religious reasons and those who are avoiding them out of fear. He writes:

I think there are likely parents who absolutely believe that vaccines are wrong in the same way there are parents who think blood transfusions are wrong. We allow exemptions for religious reasons in this country for lots of things I don’t understand, but that’s the point. I DON’T UNDERSTAND.

For example, the Amish don’t vaccinate for religious reasons; last year Amish communities in Ohio were the site of America’s largest measles outbreak in recent years, one that received barely any attention compared to the much smaller Disneyland outbreak.

6. Unvaccinated people can be restricted from certain public activities (i.e. school) during emergency situations like outbreaks.

Until recently, only a very small number of parents filed for vaccine exemptions based on their beliefs (in California, it was less than 1% from 1978 to 2000). But as the number of parents opting out has increased– along with the potential for outbreaks like we saw at Disneyland– thanks to the anti-vaccination movement, it brings up the question: what should we do when so many parents refuse to vaccinate out of fear (again, with no scientific basis) that it puts the rest of us at risk?

Some have suggested that the government make vaccinations mandatory, but, at least at the federal level, a mandate could backfire by polarizing the issue along partisan lines and lead to fewer vaccinations. We’ve seen the start of that with Chris Christie’s and other Republicans’ comments– hardly any politician will say that parents shouldn’t get their kids vaccinated (although Rand Paul’s comments came pretty close; he later walked them back), but they will say that the government shouldn’t force them to. (At the state level things are different; the state with the highest vaccination rate is ultra-conservative Mississippi, which offers no personal belief exemptions.)

vaccine exemption map

Carroll’s point is that if people have a right to opt out of vaccinations based on personal beliefs, we should be able to limit the risk that decision poses to others. In any event, the hope is that the current measles outbreak will be enough of a wakeup call to stop the anti-vaccination movement; after all, no parent wants their child to get sick from serious diseases that can be avoided.

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