See how bacterial blood infections in young kids plummeted after vaccines

To celebrate birthdays, my 2- and 4-year-old party animals got vaccinated. Measles, mumps, rubella, chicken pox, diphtheria, tetanus and whooping cough for the older one (thankfully combined into just two shots), and hepatitis A for the younger.

Funnily enough, there were no tears. Just before the shots, we were talking about the tiny bits of harmless germs that would now be inside their bodies, teaching their immune systems how to fight off the harmful germs and keep their bodies healthy. I suspect my girls got caught up in the excitement and forgot to be scared.

As I watched the vaccine needles go in, I was grateful for these medical marvels that clearly save lives. Yet the topic has become fraught for worried parents who want to keep their kids healthy. Celebrities, politicians and even some pediatricians argue that children today get too many vaccines too quickly, with potentially dangerous additives. Those fears have led to reductions in the number of kids who are vaccinated, and along with it, a resurgence of measles and other diseases that were previously kept in check.

Doctors and scientists try to reduce those fears with good, hard data that show vaccines are absolutely some of the safest and most important tools we have to keep children healthy. (Here’s a handy list of papers if you’d like to dig deeper.) A  study published online March 10 in Pediatrics shows a particularly compelling piece of data on the impact of vaccines.

In 2000, doctors began using a vaccine called PCV7, which protected children against seven kinds of Streptococcus pneumoniae bacteria. PCV13 came along in 2010, adding six more types of bacteria to the protective roster. These bacteria can cause many different illnesses such as ear infections, meningitis and blood infections called bacteremia. In young children, these infections can sometimes be quite dangerous (and hard to diagnose).

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Medical records that span these pre- and post-vaccine time periods, kept by Kaiser Permanente Northern California, offered a chance to see these pneumococcal vaccinations in action. Before the vaccine existed, 74.5 of 100,000 kids ages 3 months to 36 months got pneumococcal bacteremia. After PCV13, that number had plummeted to 3.5 per 100,000. That’s a 95.3 percent reduction.

This plunge is striking, says study coauthor Tara Greenhow, a pediatric infectious disease specialist at Kaiser Permanente Northern California in San Francisco. Along with earlier results, the new study shows that pneumococcal vaccines are highly effective, she says.

As you check out the graph, pay attention to the data points you don’t see. Those are the babies and toddlers who didn’t end up sick, thanks to a vaccine.