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The real dangers of not getting vaccines

Posted by Dr. Claire McCarthy  September 30, 2013 10:42 AM

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Thumbnail image for sick baby.jpgNot getting vaccines can be very dangerous--not just for you or your child, but for everyone around you. 

It's ironic that part of the reason we have trouble convincing some people to immunize their children these days is exactly because they are so successful. Why immunize against polio, some people say, when there are no cases of it? Vaccines are so good at what they do that it's easy to get lulled into thinking that it's safe not to immunize--because we won't be exposed to the diseases anyway.

That's plain old wrong--travelers to and from other countries bring the diseases in all the time--and it's the kind of thinking that puts everyone at risk.

When enough people are immunized against a disease, it creates something called "herd immunity": even if someone shows up who has the disease, it's hard for it to spread because most of the people around that person are immune to it. Herd immunity doesn't just stop spread,  it protects people who can't be immunized or aren't fully immunized, like newborns or people who have trouble with their immune systems. It also protects when the vaccines don't work perfectly (which can happen) or when a few people choose not to immunize.

But when lots of people stop immunizing, the herd immunity breaks down. And that's when bad stuff starts happening.

A study just published in the journal Pediatrics shows how this happened in California with pertussis, also known as whooping cough. What most people don't realize is that before we started immunizing against pertussis, it was the leading cause of child mortality in the US. In 1934, there were more than 265,000 cases of pertussis; in 1974, immunization had brought that down to 1010. 

But in the early 2000's, the numbers started going up again--and in 2010, there were more than 9,000 cases in California alone, a third of all the cases in the country. There were various reasons for this, including waning immunity from the vaccine (we give booster doses now), but part of the problem was that more people weren't immunizing their children.

Between 2000 and 2010, the number of children whose parents chose not to immunize them--for reasons besides medical reasons--tripled from 0.77 percent to 2.33 percent. This seems low--and it would be, if the people were evenly spread out over the state. But they weren't; many of them lived in the same areas, meaning that in some communities the rate of not immunizing was as high as 84 percent.

The researchers who did the study found that cases of pertussis were 2.5 times more likely to happen in areas of the California where there were groups of people who didn't immunize. The herd immunity broke down--and children died.

When I talk to people who are hesitant about immunizations, what I mostly hear is worry about side effects. It's certainly true that vaccines, like any medical treatment, can have side effects. Luckily, they are rare--but they are certainly possible.

However--and this is what people don't think about--the risk of side effects from the vaccine are always lower than the risk of complications from the disease. And you can't necessarily count on not catching the disease. It's not just pertussis; we are seeing more measles, too, and other vaccine-preventable diseases. And influenza is a real risk every single year.

While you or your child might weather influenza, chicken pox, pertussis or whatever without too much trouble, the newborn next door, or your own newborn, or your frail grandmother or the child at school being treated for cancer might not. The immunization decision isn't just about you or your child. It's about every single person around you.

So if you are considering skipping any immunizations for your child or yourself, think hard before you make that potentially dangerous decision. Read not just about vaccines but about the diseases they prevent; there's lots of information about both on the website of the Centers for Disease Control and Prevention. Talk to your doctor if you have any questions at all.

Remember: vaccines have saved thousands and thousands of lives. They might already have saved yours or your child's, whether you are immunized or not.

Is there something you'd like me to write about? Leave me a message on my Facebook page--and "like" the page for links to all my MD Mama blogs as well as my blogs on Thriving and Huffington Post. 

This blog is not written or edited by or the Boston Globe.
The author is solely responsible for the content.

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About MD Mama

Claire McCarthy, M.D., is a pediatrician and Medical Communications Editor at Boston Children's Hospital . An assistant professor of pediatrics at Harvard Medical School and a senior editor for Harvard More »

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