How Herd Immunity Helps Shield Those Who Can't Be Vaccinated from Diseases

Aug 19, 2016

Credit US Army Corps of Engineers/flickr

Not everyone can get vaccinated. Some people are allergic to vaccines, others are receiving treatment for diseases like cancer, and some people are just too young. But doctors and state health authorities require public school students to be vaccinated—unless their parent signs a waiver exempting them from immunizations. The number of those exemptions is rising in Texas.


If there is an outbreak of disease, those people who can’t be vaccinated for health reasons are the most at-risk of contracting that illness. That is, unless the majority of people around them are immunized, which protects the outbreak from spreading – a concept called herd immunity.

“A lot of people say, ‘Well, if my child if your child is immunized, why do you care if mine is or isn’t?’ And, really, that’s a short-sighted view,” says Anne Dragsbaek, president and CEO of The Immunization Partnership, a nonprofit that supports high immunization rates. “If you have enough people in the community that are immunized, they will act as a shield and they will prevent the disease from spreading to those among us who can’t be immunized.”

The number of Texas students who are not immunized has risen drastically from around 3,000 in 2003 – when the state allowed parents to submit conscientious exemption forms, if they decided to not vaccinate their children for non-medical reasons – to around 45,000 last year. Dragbaek says that’s problematic for those who can’t be immunized – particularly, babies who are particularly vulnerable to diseases like measles. 

“So, if you have a kindergartner who contracts measles at their school, that kindergartner could take it home to the 6-month-old baby at home and that could really have some disastrous consequences,” she said.

Brennan Griffin is sending his child to public school next year—and is concerned about the rise in unimmunized kids in Texas.

“You get up above 90 percent of an area vaccinated, then the disease then most diseases cant take root,” he said. “Once you get down below 90 percent, there are several diseases that can start to take hold and sometimes vaccinations don’t work for just idiosyncratic reasons for each child. So, they’re putting more than just their own child at risk when they’re not being vaccinated.”

Credit Centers for Disease Control

The increased numbers appear to reflect a growing belief among some parents that vaccines can harm their children. Many attribute that anti-vaccination sentiment to the proliferation of a discredited 1998 study that falsely linked some vaccines to autism. The man who conducted that study, Andrew Wakefield, was stripped of his medical license in Britain and now lives in Travis County. 

Last week, KUT reported on the non-immunization rates in Austin Public schools. Two South Austin schools Zilker Elementary and Sunset Valley Elementary had the highest rates, each had around 10 percent of students who were not vaccinated for non-medical reasons last year.