Nearly 75% Of Kids May Have Had COVID—but That Doesn’t Mean They’re Immune

Mom helping her child do at-home COVID-19 tests.

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Key Takeaways

  • The CDC estimates that three in four kids and more than half of all Americans have been infected with COVID-19. 
  • Infections in children increased at higher rates during December 2021 and February 2022 when the Omicron variant was considered the most dominant strain in the U.S. 
  • Health experts continue to urge families to get vaccinated and boosted, including those who may have been previously infected with COVID-19. 

It’s estimated that three out of every four children in the United States have been infected with COVID-19 and more than half of all Americans have also had signs of previous infections, based on a recent report by the Centers for Disease Control and Prevention (CDC).

Researchers studied blood samples from more than 200,000 people and looked for virus-fighting antibodies made from infections, not from vaccines.

They found between December 2021 and February 2022, when the Omicron variant was the most dominant in the U.S., the percentage of people who developed antibodies from infection/exposure to COVID-19 increased dramatically.

“The omicron variant of SARS-CoV-2 swept through our country around the winter holidays and month of January 2022,” Anna Sick-Samuels, MD, MPH, assistant professor of pediatrics at Johns Hopkins Medicine, told Verywell. “Many people who had not previously been infected became infected during this time.”

Specifically, for people of all ages, about 34% showed signs of prior infection in December, however, that increased to nearly 58% in February. 

Over that same time period, children under the age of 12 were reported to have the most dramatic increase. The number of children who developed antibodies from a previous infection increased from 44% in December to 75% just two months later.

“That number doesn’t surprise me, especially given how more contagious, subsequent variants have been compared to the original virus identified two years ago,” Arunima Agarwal, MD, a board-certified pediatrician based in New York, told Verywell. “As a pediatrician, when parents take their kids to daycare for the first time, they have colds every week, every two weeks so that number does not shock me.”

Why Are Children Getting Infected at Higher Rates?

According to the CDC, the Omicron variant spreads more easily and is more contagious than the original COVID-19 virus and the Delta variant. Because of this, Agarwal said, more people, including children, got infected.

"It’s an airborne virus, which makes contact very easy. We had lockdown measures at the beginning but they have waned especially in the last six to 12 months,” Agarwal said. “Masking guidelines have also decreased in most states so that just makes it much easier to contract the virus.”

Vaccine availability and authorization may have contributed to why children were getting infected with COVID-19 at high rates between December and February, too. It wasn’t until October 29, 2021—when Pfizer was granted emergency use authorization for a pediatric COVID-19 vaccine—that children between the ages of 5 to 11 could get vaccinated.

“If an individual is unvaccinated, whether that be a child or adult, then they are more likely to get the virus,” Agarwal said. “The vaccine was only approved for kids aged 5 and up around Thanksgiving, so around December most children were not vaccinated with one dose, let alone two doses to complete the course of the vaccination series.”

Attending school, being in close proximity with other students, and sharing toys could be other reasons why many children have contracted COVID-19 and developed antibodies over time, Agarwal explained.

Will Prior Infection Provide Immunity to Kids? 

If someone gets infected with COVID-19 including children, they should develop some immunity and ability to fight off a particular infection using antibodies.

Agarwal said even if a child develops antibodies from a natural infection, it typically only lasts around four to six months. However, the length of immunity is different for every child.

The CDC states even though immunity and protection are not fully understood, antibody development after an infection likely occurs and can provide protection for at least six months. Still, this previous protection may vary as new variants emerge.

“COVID is still going to be around in four to six months so you want your child to be protected beyond that,” Agarwal said. “There are extensive studies showing that the immunity from the vaccine is more robust and longer-lasting compared to natural infection.”

What This Means For You

Children and teenagers who have already had COVID-19 may have developed some immunity from natural infection. But, if they are eligible, they should still get vaccinated. Natural immunity in children can vary and may change depending on the prominent circling variant.

Should Children Still Get Vaccinated and Boosted? 

While natural protection provides some immunity for a short period of time to children, experts still advise parents to get their children vaccinated and boosted, if eligible.

That’s because vaccines are known to help prevent severe infections requiring hospitalizations across the age ranges for which they have been approved (ages 5 and up), according to Sick-Samuels. Specifically in children, the mRNA vaccine also prevents developing a severe complication of COVID-19 called multisystem inflammatory syndrome in children (MIS-C), where the body develops a harmful inflammatory response that can lead to organ failure and very severe illness in previously healthy children.

Sick-Samuels added the immune response after actual infection in children is not consistent. Particularly, scientists are still learning why some children do not develop a lasting immune response if they have previously been infected compared to other children that do. However, one idea is that a more generic part of the immune system called the innate immune system acts faster in children to stop the virus before it can cause a bigger more involved infection, Sick-Samuels said. 

It is also not clear how long protective immunity from actual infection lasts in children and infection from one variant may not protect against a new variant. Since the immune response to vaccines is more consistent compared to natural infection, Sick-Samuels said she still recommends the vaccine for children even if they have had a prior COVID-19 infection.

Agarwal noted there have been reports that some teenage boys and young men who received the mRNA vaccine developed myocarditis, which is inflammation of the heart muscle. However, if you were to get myocarditis from a natural infection with COVID, “it is much more dangerous than the very small risk of it occurring secondary to the vaccine.” 

“Not vaccinating children is taking a risk because although many children may have a mild flu-like illness or upper respiratory viral symptoms, some children will get a severe infection and some will develop MIS-C,” Sick-Samuels said. “The pandemic led to such significant interruptions in children’s typical activities; vaccination is another way to ensure we can continue normal daily activities.”

The vaccines have been safe and effective against severe illnesses in older age groups, however, scientists are still waiting to see how the vaccines perform in the youngest ages.

Currently, everyone ages 5 years and older are eligible to get vaccinated against COVID-19, but children between 5 and 17 are only eligible for the Pfizer vaccine. At this time there is no approved vaccine for children under the age of 4.

Children older than 12 can also get a COVID-19 booster shot and those between 5 and 11 who are immunocompromised should talk with a healthcare provider to see if they may be eligible for a booster.

“Children are part of families and reducing the risk of bringing home the virus may also reduce the risk of transmission to their family members,” Sick-Samuels said. “Thousands of children have lost parents and caregivers to COVID-19 in the past two years. Anything we can do to support the health and well-being of children across the country should be a priority.”

Beyond vaccination, Sick-Samuels said there are other ways to reduce the risk of COVID-19 transmission, including not being in close contact with others with cold symptoms, wearing a mask when indoors and in close contact with other people, and handwashing often.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Centers for Disease Control and Prevention. Omicron variant: what you need to know.

  3. Kim C, Yee R, Bhatkoti R, et al. COVID-19 vaccine provider access and vaccination coverage among children aged 5-11 years — United States, November 2021-January 2022. MMWR Morb Mortal Wkly Rep. 2022;71(10):378-383. doi:10.15585/mmwr.mm7110a4

  4. Centers for Disease Control and Prevention. COVID-19 vaccine recommendations for children and teens

By Alyssa Hui
Alyssa Hui is a St. Louis-based health and science news writer. She was the 2020 recipient of the Midwest Broadcast Journalists Association Jack Shelley Award.