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5 Things You Should Know About Vaccines

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Young girl with partial paralysis, caused by polio. (Courtesy Boston Children's Hospital)
Young girl with partial paralysis, caused by polio. (Courtesy Boston Children's Hospital)

Take a hard look at the picture. These are images we don't see in this country at all anymore. But until the polio vaccine came along in 1955, children and adults paralyzed from polio were fairly commonplace. (FDR, anyone?) Today, vaccines are now a victim of their own success. Because they've so successfully wiped out devastating childhood illnesses, people seem not to fear those illnesses anymore. Now we have parents who decide not to have their children vaccinated.

As KQED News has reported this week, the number of parents in Marin County opting out of vaccines for their children is climbing. Last year, 7.8 percent of Marin parents opted out, 1 percentage point higher than the previous year. At present, California has one of the most lenient laws in the country to allow parents to decline vaccinating their kids: the "personal belief exemption." It's a short statement that says vaccinations are against a parent's beliefs. (A new law amends this exemption somewhat; more on that below.)

On Thursday, KQED's Forum took up the question of vaccines, and it was clear that many people remain confused on some key points.

1. What is herd immunity?

This simply means that enough people are vaccinated against a contagious illness that most of the community is protected -- including those who cannot be vaccinated, such as newborn infants and people with compromised immune systems. And there are a lot of people with compromised immune systems, including pregnant women, people being treated for cancer, HIV/AIDS patients and more. The percentage of people who need to be vaccinated to create herd immunity for many childhood illnesses is high -- 90 percent, according to the federal government's Healthy People 2020 goals. The National Network for Immunization Information draws a striking contrast between two outbreaks of measles. In 2003, an infected Japanese tourist arrived in the Marshall Islands, where vaccination rates were below 75 percent (i.e., below a herd immunity level). An epidemic ensued with more than 700 cases, 56 hospitalizations and three deaths. In the same year, there were two separate introductions of measles in Mexico. But vaccination rates were above 95 percent there. Only 41 people contracted measles as a result. Vaccination matters.


2. Does state law require kids to be vaccinated? And can I find out how many kids are not vaccinated at my child's school?

The short answer is "yes" to both questions. State law requires that children at all public and private schools be fully immunized before they start kindergarten. The California Department of Public Health sets the list of vaccines, but essentially follows national guidelines from the federal government and the American Academy of Pediatrics. A very small number of children cannot be vaccinated for medical reasons, and they are eligible for a "personal medical exemption." But in California, the bigger problem has been the personal belief exemption, or PBE. This is the last school year that parents will be able to avoid vaccination for their children simply by signing a piece of paper saying they are opposed to vaccines. Starting in January, when a new state law goes into effect, parents will also need to provide a signed form from a health care provider who will have explained the benefits and risks of vaccines as well as the risks of communicable diseases. While it's plausible this law won't make a difference to the dedicated anti-vaccine crowd, it may well make a difference to people who have found conflicting or inaccurate information on the Internet or other sources (or parents who find it easier to drop off a signed statement instead of vaccinating their kids). The state of Washington passed a similar law in 2011 and their opt-out rate has dropped by almost 40 percent. Here in California, the state compiles data on vaccination rates for public and private schools statewide, and you can look up your own child's school.

3. I disagree with the vaccination schedule and have developed my own. Is this a problem?

The CDC's Advisory Committee on Immunization Practices reviews the vaccine schedule every year. What many people don't know is that there is some flexibility built into the schedule. For example, the third dose of the hepatitis B vaccine can be given between 6 and 18 months of age. The third dose of polio can be given between 4 and 18 months. If you adjust the schedule on your own, you are putting your child at risk of developing a serious illness that could have been avoided. CDC information allays concerns about vaccines overloading a child's immune system:

Every day, a healthy baby’s immune system successfully fights off millions of antigens—the parts of germs that cause the body’s immune system to go to work. ...

Vaccines contain only a tiny fraction of the antigens that babies encounter every day in their environment, even if they receive several vaccines on one day.

4. If your child is vaccinated, why do you care if mine is not?

While vaccines are highly effective, they are not 100 percent effective. This goes back to herd immunity described above. In order to protect the entire community, we need for as many people to be vaccinated as possible. Again, it's not just about protecting children. People who deny vaccinations to their children put pregnant women, cancer patients, AIDS patients and even healthy people at risk of disease. Here's just one example about one of the "newer" vaccines, against Haemophilus Influenzae type b, also known as Hib. Before 1985 -- before the vaccine --  Hib caused serious infections in children, including 12,000 cases of meningitis and 7,500 cases of pneumonia. Compare that with 2002, when there were just 34 cases of Hib disease.

5. What about the link to autism? Or other problems from vaccines?

The public confusion about a connection between vaccines and autism stems primarily from one major study. In 1998, the Lancet published a study from British researchers which implicated the measles, mumps and rubella vaccine as increasing the risk of autism. There's just one problem: One of the researchers on that study, Dr. Andrew Wakefield, was investigated. Britain's General Medical Council concluded his "conduct was irresponsible and dishonest," and the study was later retracted. But Wakefield's damage is hard to undo. The concern continues to circulate.

As for other side effects of vaccines, yes, they exist. Like everything else in life, vaccines, too, come with risks of adverse effects. The risks are small, but not zero. The CDC and the FDA co-sponsor a reporting system to track vaccine side effects.

Now, back to polio for a minute. If you really want to feel the fear of life before the polio vaccine, watch this excellent segment from RLTV's documentary Polio Revisited. It will break your heart.


This post has been updated to clarify the role of the Lancet study in the public confusion around vaccines and autism.

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