What is a vaccine, really?
Answering a question posed by my three year old niece…
This past weekend, I took my parents’ two cats to the veterinarian for their annual vaccines. My three-year-old niece tagged along, and as we walked to the truck at the end of the visit, she looked up at me and asked, “Aunt Camille, what is a vaccine?”
Readers, the way I stumbled, stopped, and started again to answer this question using only terms she would understand (we adults forget what we didn’t used to know)! I thought this might be useful to others, so I’m posting my answer. In order to answer my niece’s question about what a vaccine is, I also had to explain why we vaccinate.
We vaccinate because there are germs everywhere. These germs are very, very small and live on and in our bodies, in the bodies of animals, and in things like water or dirt. Some germs can cause us to get very sick or even die. A long time ago, some people realized that bringing a healthy animal or human into controlled contact with a germ could keep us from getting sick, shorten how long we are sick, or prevent us from dying from an illness. This is because our bodies build memories of germs we have come into contact with.
Once your body recognizes a germ - maybe because you’ve gotten a vaccine or because you’ve been sick with that germ before - your body starts to fight it off to keep you healthy. If you’ve had a vaccine for this particular germ- be it flu, COVID-19 or measles -your body can respond more quickly if/when you come into contact with the germ. This quick response means you’re less likely to get very sick, more likely to get better quickly, and much less likely to die.
A vaccine is usually given as a shot. This shot contains something of the germ you want to be protected from (like a killed germ or one adjusted to be less dangerous) which makes it less dangerous than just getting sick with germ would be (although that also builds immune memory). Once in the body the vaccine causes a memory to be formed known as an antibody. These antibodies are what protects you if/when you come into contact with the germ later in life. Some immune memories last longer than others (once you’ve completed a measles vaccine series you’re protected for life), and some germs are more changeable than others which is why we have to be vaccinated every year for the flu.
Have a science or health question you want answered in plain English? Please leave a comment!
Until next Wednesday, I’m your host at Health in Plain English- Camille Ledoux, PhD -an infectious disease biologist with a passion for science communication and helping my community.