Now that the CDC is officially recommending COVID-19 vaccines for kids ages six months and older, your children might have a few questions about the science behind how vaccines of all types work. One of the best approaches? Be calm and straightforward with them.
“If adults are matter-of-fact about vaccines, kids will likely be less nervous about them,” says Laura Faherty, a health policy researcher at the nonprofit RAND Corporation and an assistant professor of pediatrics at Boston University School of Medicine.
When she explains vaccines to her two young children and patients, she starts by relating them to medical treatments they’re already familiar with. “I often say that there are some medicines that we take when we’re sick to help us feel better,” Faherty says. “Vaccines are like medicine that we take to keep us from getting sick in the first place.” (Find out how to help kids get over a fear of shots.)
Why do we need vaccines?
Faherty advises beginning your conversation by emphasizing to children just how amazing their bodies are. “Our bodies are strong and do a great job keeping us safe from germs,” she says.
Then try this analogy: Our immune system is our body’s defense system, and the immune cells are our body’s soldiers. The soldiers battle various invaders, such as viruses and bacteria, that want to take over our immune system and make it their prisoner, which is why our bodies become sick.
But sometimes those immune cell soldiers need a teacher. Vaccines train our immune system to defend against dangerous invaders—also called pathogens—to keep our bodies healthy.
“After you get a vaccine, your immune system soldiers learn how to fight off a specific infection, so if you're exposed to that germ in the future, you don't get sick,” says Tanya Altmann, an assistant clinical professor of pediatrics at UCLA Mattel Children's Hospital and a spokesperson for the American Academy of Pediatrics.
How do vaccines work in the body?
First, take a step back to introduce the concept of cells. Explain that several different kinds of cells move around inside the body. Red blood cells deliver oxygen to our tissues and organs; platelets help the body heal.
White blood cells fight off infections. Understanding how they work is key to understanding what vaccines do in the body. Two of the main types of white blood cells are B-cells and T-cells.
“B-cells, when exposed to the vaccine, will put out what we call antibodies,” says Sallie Permar, chair of pediatrics at Weill Cornell Medicine and New York-Presbyterian. “Those antibodies bind to a virus or bacteria and then prevent it from infecting another cell or spreading around the body.”
Permar says T-cells help activate the B-cells so they can make lots of antibodies, as well as develop special cells that kill cells that have already been infected with a virus. T-cells also have good memories, so after they fight an invader, they remember how to defeat it if it comes back.
Some vaccines contain weakened forms of a live virus or bacteria that aren’t strong enough to make a person with a healthy immune system seriously sick. This gives our defense system an easy enemy to practice against, so when the dangerous form of the germ tries to infect the body, the soldiers are already battle-tested against it.
Why do vaccines always seem to come in a shot?
Many kids (and adults) hate shots, but explaining to your child why doctors use them may help make the process less scary.
Though a few nasal and oral vaccines exist, vaccines delivered through needle injections into the arm have shown to be the best way to teach your immune system to defend itself.
“Most vaccines are given as a shot because if we ate or drank them, our tummies would think they’re food and mush them up,” Faherty likes to tell kids. “When they’re put into our bodies in a shot, the medicine stays strong and helps our body keep the germs from making us sick.”
Why do we need to take some vaccines every year and others just once?
Ideally, you’d only need one dose of a vaccine to protect yourself for the rest of your life. But that’s not necessarily what happens. “With some vaccines, or some infections, your soldiers need reminders,” Altmann says. “By giving your body future doses of a vaccine and future reminders, it keeps your soldiers strong and remembering how to fight off that specific infection.”
Sometimes—as with the Pfizer-BioNTech and Moderna COVID-19 vaccines—multiple doses are needed. That first shot might get your soldiers producing some antibodies, Altmann says, but a second shot is needed to really get them into defense mode and make sure your body’s armor is all the way up.
What’s herd immunity?
Vaccines aren’t just for our own protection—they can protect entire communities and nations. When enough people are vaccinated against a deadly disease, the spread of that disease is limited, which protects other people who might be unable to get vaccinated. That’s what we call herd immunity.
Try explaining this using school as an example. “There might be one person in your class who—because of the way their body is made up, or because they have a specific illness, or they're taking medications—can’t get vaccines,” Altmann says.
But if everybody else in your class who’s strong and healthy gets vaccinated, Altmann says “you can help protect that one person.”
By expanding the classroom example to a town, a state, or even a country, you can show your kid why the COVID-19 vaccines can help protect everyone and—along with mask-wearing and social distancing—bring an end to the pandemic.
Editor’s note: This article was originally published December 7, 2020, and has been updated to include information about the Centers for Disease Control and Prevention's recommendation that children six months and older receive a COVID-19 vaccine.