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Does the COVID-19 vaccine protect kids from variants of the virus like delta and delta plus?

Katherine Williamson, MD, FAAP


​​There are many variants of COVID-19. Right now, the delta variant is the most common variant that is infecting people. The COVID-19 virus has been changing (mutating) over time. Sometimes, a virus mutates to become stronger or easier to spread from person to person. Since summer 2021, the delta variant has caused COVID-19 infections to spread quickly to more kids and adults.

Fortunately, the COVID-19 vaccine is very effective for kids and adults. Yes, even against the delta variant. Getting the COVID-19 vaccine also helps stop the virus from spreading from adults and kids to others. As more people are fully vaccinated, cases start to drop.

In the clinical trial for children 5 to 11 years, the COVID-19 vaccine was over 90% effective in stopping infection from the delta variant.

When a virus changes, new variants form and other variants fade away. New variants will continue to emerge. Scientists in the U.S. keep track of all of variants of the virus here and around the world. Right now in the U.S., the delta variant is the main variant of the virus that causes COVID-19. Some states have identified "delta plus" variants that are related to the delta variant.

Why is the delta variant affecting younger people?

The delta variant causes more infections and spreads faster than the other forms of the virus that were infecting people when the pandemic began. Here is what we know:

  • We know that children under 5 years old cannot be vaccinated yet. Compared to older kids, children under 4 years old are at most risk of being hospitalized if they are infected. Nearly all of the children who have been hospitalized for COVID-19 illness are not vaccinated.

  • We know that the COVID-19 vaccines work very well against all variants.

  • We know that the delta variant can still infect a small group of fully vaccinated people. This is called a breakthrough infection. Fortunately, fully vaccinated people who do get infected mostly have milder illness. They are less likely to need hospital care — even with the Delta variant. We know how to stop severe illness, hospitalization, and death from COVID-19! Everyone who can get vaccinated, should get vaccinated. When more people are immune, the virus cannot mutate as fast or make other new, more contagious variants. Even people who had COVID-19 illness need to get vaccinated, too.

The delta variant is keeping life stressful for families with young kids

Here's how parents can help prevent COVID-19 from spreading to others around them who may not be fully protected:

  • Get your children vaccinated as soon as they are eligible. Right now, children in the U.S. who are eligible for the vaccine can receive the COVID-19 mRNA vaccine from Pfizer BioNTech.

  • Make sure that everyone around your unvaccinated children is vaccinated. Children are only as safe as those around them.

  • Remind everyone 2 years and older to keep wearing face masks in indoor public places and crowded outdoor places with others who have not been fully vaccinated. If you are fully vaccinated and you live in an area of substantial or high transmission, wearing a mask can help protect you and others from spreading the delta variant.

  • Keep reminding children to wash their hands before eating or touching their face.


By doing your part to reduce the risk of spread in your family and community, you are keeping young children, along with elderly and immune compromised people, safe during a difficult time. If you have any questions about your child's health or safety, contact your pediatrician. Our focus is on keeping kids healthy and safe, and we are always here to help.

Katherine Williamson, MD, FAAP

Katherine Williamson, MD, FAAP, is president of the Orange County Chapter of the American Academy of Pediatrics. She is a Primary Care Network Informaticist at Children’s Hospital of Orange County.​​​ Follow her on Twitter and Facebook​: @kate4kidsmd​​​

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The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
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