How Old Do You Have To Be To Get Vaccinated

This post was last updated November 4, 2021.

The FDA has granted emergency use authorization to three COVID-19 vaccines, including for children as young as 5 years old. This is a huge step in our fight to end the pandemic.

Connecticut Children's Physician-in-Chief Juan Salazar, MD, MPH, answers common questions from families.

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What ages has the COVID-19 vaccine been authorized for?

Pfizer's vaccine has been authorized for ages 5 and up (with full FDA approval for ages 16 and up). Here are FAQs for ages 5 to 11, and FAQs for ages 12 to 15.

Moderna and Johnson & Johnson's vaccines are currently authorized for ages 18 and up.

What about ages 0 to 4? When can we expect a COVID-19 vaccine for infants and younger kids?

We expect to see data from vaccine tests in children as young as 2 years old later this fall or winter. It's possible we'll see information on the vaccine in children as young as 6 months old by the end of the year.

Why isn't a COVID-19 vaccine available to all kids at the same time as adults?

Children's immune systems are very different from adults', and their immune responses can be different at different ages, from infancy through the teenage years. So the research that's been done on the COVID-19 vaccine for older ages needs to be repeated in children of younger ages.

This process can take awhile, especially for very young ages, which are usually tested last.

Nurse adminsters COVID-19 vaccine to Connecticut Children's patient

How do Pfizer's and Moderna's COVID-19 vaccines work?

Both Pfizer and Moderna's vaccines are made using the same technology: They inject a genetic molecule called mRNA, which causes a person's cells to create a viral protein (called a "spike") that triggers the desired immune response. There is no live virus involved – the mRNA molecule is simply a messenger that tells the body how to create an immune response. Then it's quickly broken down by the body and disappears.

This is a new technology for vaccines. Because of the mRNA component, which breaks down very easily, the vaccine must be kept cold. The Pfizer vaccine is stored in a freezer at "ultra cold" temperatures, minus-80 degrees Celsius (minus-112 degrees Fahrenheit). The Moderna vaccine can be stored in a regular refrigerator.

How does Johnson & Johnson's COVID-19 vaccine work?

Like the Moderna and Pfizer vaccines, the Johnson & Johnson vaccine triggers an immune response that blocks COVID-19 infection. But it uses a method that's been around for years: injecting a modified virus ("adenovirus") into the body. The injected adenovirus, which is similar to a common cold or flu virus, has been disabled – in other words, it can't make copies of itself or make the person receiving it sick. It's simply a messenger: It contains DNA instructions for a "spike" protein. The body then creates the protein, which triggers an immune response to protect against COVID-19.

This type of vaccine doesn't need to be stored at super-cold temperatures, which makes it easier to transport and store than Moderna's and Pfizer's vaccines.

Research and testing on adenovirus-based vaccines has been ongoing for decades. There are several existing adenovirus vaccines in general use, including one for Ebola (also by Johnson & Johnson), which has been used safely on infants.

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How many doses does the COVID-19 vaccine take to be effective?

The authorized vaccines by Pfizer and Moderna require two shots: an initial dose followed three or four weeks later by a second shot. The vaccine by Johnson & Johnson requires just one shot. For all of these vaccines, it takes up to two weeks after the final dose for the body's immune system to respond fully. See below for how the vaccines may work against newer variants.

> Related: Ask a Pediatrician: How Can I Tell if My Child Has the Flu or COVID-19?

Are the COVID-19 vaccines safe? Have there been any serious side effects?

Before authorizing the vaccines, health officials closely reviewed all safety data from Pfizer, Moderna, and Johnson & Johnson's clinical trials and concluded that the vaccines are very safe for most people. That continues to be true after hundreds of millions of doses have been administered in the U.S. alone.

Any serious side effects have been rare:

The CDC has reviewed rare – and mostly mild – cases of myocarditis and pericarditis in vaccinated teens and young people. They continue to recommend the COVID-19 vaccine, because protection from the virus outweighs any potential risks. A recent study shows that COVID-19 infection is actually much more likely to cause myocarditis than the vaccine.
Additionally, the CDC and FDA examined rare reports of adults (mostly women ages 18 to 49) who developed a blood clotting disorder after receiving the Johnson & Johnson vaccine. They determined the benefits of receiving the vaccine outweigh the known and potential side effects, which appear to occur in extremely rare cases.

The CDC has established an independent group of experts to review all safety data as it comes in, and provide regular safety updates and advice.

When I made the decision for myself about whether or not to get the vaccine, I weighed the risk of COVID-19 – which we know has caused very serious illness and death for a lot of people – against the risk of the vaccine – which seems to be very effective and safe based on all the data so far.

I was excited, and grateful, to choose the vaccine.

Should my child get the vaccine, once it's available to them?

Yes. It's important for kids and teens to get the COVID-19 vaccine.

While most children and adolescents do not become seriously ill from COVID-19, a small number do get very sick and need hospitalization. Even those who feel fine still miss out on school and important social interactions, and may experience troubling side effects like headaches or loss of taste and smell. There may also be long-term impacts of COVID-19, which we're currently studying at Connecticut Children's.

The vaccine is the best way to keep your child and family safe from all of these risks, and help our community achieve widespread immunity.

Are there any common side effects of the COVID-19 vaccine, like a sore arm after a flu shot?

Some people have mild to moderate side effects after the second dose, like soreness in their arm, chills, low-grade fever, fatigue or headache in the next 24 hours. These side effects are a normal part of the body's immune system response, and commonly occur with many vaccines like the regular flu shot.

Will the COVID-19 vaccine wear off every year, like the flu shot?

Great question. The CDC recently recommended booster shots for older adults, individuals with certain underlying health issues, and several other groups who are considered higher risk. It seems possible that people will need to get vaccinated against COVID-19 annually, similar to a flu shot, but that information is still not confirmed. So stay tuned.

Once you get the COVID-19 vaccine, can you still spread COVID-19 to others?

You'll be much less likely to spread COVID-19 after vaccination, but it's still possible. That's why the CDC still recommends masks and other precautious in some situations, like when you're using public transportation or visiting a vulnerable family member.

Is the current COVID-19 vaccine still effective against the Delta variant and other new strains?

All coronaviruses, including COVID-19, tend to mutate and evolve over time. This means that the genetic blueprint, or genome, of the virus is changing.

The current vaccines are slightly less effective against the Delta variant, but they still offer strong protection against severe illness.

Has Connecticut Children's vaccinated its healthcare heroes?

Yes! I was proud to be among the first to receive my COVID-19 vaccine. We know how important the vaccine is to ending this pandemic – and we're proud to do our part.

Where can I learn more about the COVID-19 vaccine and kids?

Check out our COVID-19 Vaccine Updates, including details about vaccine clinics and lots of resources for your family. Remember that all kids age s 5 and up can now get the vaccine. If that includes your child, please schedule their vaccine today. It's the best way to keep them safe from COVID-19.

If you have questions about coronavirus and your child, call Connecticut Children's 24-Hour Pediatric COVID-19 Hotline at833.226.2362.

And don't delay your child's care! Connecticut Children's offers Video Visits in more than 30 specialties, and works around the clock to keep your child safe and sound at every in-person appointment.

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Related links:

FAQs: The COVID-19 Vaccine for Ages 5 to 11
FAQs: The COVID-19 Vaccine for Ages 12 to 15
Is Your Child Scared to Get Their COVID-19 Vaccine? 13 Tips to Prevent Fear of Needles
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