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Vaccines: How They Work and Why You and Your Child Need Them

October 18, 2017

Doctor administering vaccination to a child

With back-to-school season already in full swing and flu season following closely behind it, I’ve been getting a lot of questions from my patients about vaccinations. While topics related to vaccinations have become hotly debated in recent years, the most important question I still answer is: What are vaccinations?

Listen in to Dr. Joseph Chavez Carey discuss vaccinations on WJGK Radio:

What are Vaccinations?

Vaccinations are, fundamentally, treatments that help us prevent infection. The way that they accomplish this is really quite interesting!

Vaccines are medical agents administered by physicians, made in laboratories and controlled by the FDA, which manipulate your body’s natural defenses to fight disease. Your immune system, your white blood cells, your antibodies – they all have a certain capacity to build memories, or an understanding, of the infections you get. They do this so that the next time you get exposed, your body is equipped to prevent that illness. Basically, vaccines harness that natural machinery within your body to prepare our response and attack to infections we have not encountered naturally.

When we get vaccinated, we are administered a weakened version of an infection that basically mimics the way it would act inside our body if we were exposed to it in our everyday life. The vaccine doesn’t actually cause the infection, but introduces enough of it so that the body goes into what can be called a practice or rehearsal for fighting the infection. Our immune system is making those memories; learning about the particular bacteria or virus being introduced by the vaccine. Then, if a person is actually exposed to the illness, the body already knows how to respond, and can prevent or greatly diminish the symptoms.

Are Vaccines Safe For My Child?

I also get asked a lot of questions about whether or not vaccines are safe, many of which are related to parenting. As a parent myself, I completely understand. Rest assured, vaccines are safe and have a long history of safely and effectively preventing, and even eradicating, certain dangerous infections. At the same time, every vaccine does have its own list of very rare, and very specific, side effects, which is why your medical provider will carefully go over a questionnaire with you before you or your child is vaccinated. People with weakened immune systems or histories of certain allergies, for example, could be advised to avoid certain vaccinations.

Because a vaccine is mimicking the behavior of an infection, it is possible that some people may experience some general symptoms such as short-term fatigue after an injection; maybe even a low-grade fever. Some people report feeling a little bit crumby for a day afterward, and there can be some mild pain at the site of the injection. But, those are the most common side effects.

The thing to understand, however, is that vaccinations are far more effective for their purpose than they are dangerous. I point out to patients that even when I was a kid in the 80’s, we still had many diseases that we just don’t see much anymore. For example, the way we manage fevers in infants today has changed because certain virulent bacteria that used to cause things like meningitis and other serious brain infections in infants have become so uncommon now thanks to these immunizations. So, we’ve seen powerful proof of the effectiveness of vaccines, even in our own lifetimes.

And, here are two more hot button items patients often ask me about:

  1. Should I not get vaccinated if I’m sick? Usually, it’s best to go ahead and get the vaccination, even when a little sick. The CDC suggests waiting in the case of severe illness or if you have a notably high fever. With a run-of-the-mill cold, it’s better to get it done. Let your doctor make the judgement call instead of postponing without consultation.
  2. Does breastfeeding really pass along immunities from mothers to their babies? Yes, totally true and another great thing about breastfeeding. This actually begins even before breastfeeding. The antibodies contained in the TDAP vaccine, which we call the “baby shot” because expectant moms receive one around the 28-week point, are passed along to the developing baby and help prevent pertussis (whooping cough). Breastfeeding is not always easy for moms, but if they are able to do it, the passing along of immunities is one of its tremendous health benefits.

Should I Spread Out My Child’s Vaccinations?

Finally, when it comes to scheduling vaccinations for you or a child, I advise people to follow their doctor’s advice. No need to try and game the system by splitting them up to spread them out over time. What can happen with that approach is that you stand an increased chance of missing a vaccination and then all of a sudden realizing you or your child are behind schedule. The acceptable windows for vaccinations in children are typically within a couple of months of a certain age, depending on the vaccine. There is some flexibility there, but you want to be sure to stay as close to the timeline laid out by your doctor as possible, to avoid being left vulnerable.

If you or your child is due for a vaccination, I encourage you to go into the appointment with the confidence that immunizations are safe and effective. But, be your own best advocate and always feel comfortable asking your provider every question you have about any care you or your child will be receiving.


This article was authored by Joseph Chavez Carey, MD of Orange Regional Medical Group.

Joseph Chavez Carey, MD, FAAFP of Orange Regional Medical Group Primary Care team.Joseph Chavez Carey, MD
Dr. Chavez Carey is an Orange Regional Medical Group Primary Care Physician. He is Board-certified in Family Medicine, Fluent in Spanish.

He received his medical degree from New York University School of Medicine, New York and completed his internship and residency at Contra Costa Regional Medical Center, California.

To make an appointment with Dr. Chavez Carey, please call 845-333-7830.

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