--- title: Pfizer Starts COVID-19 Vaccine Tests in Children Under 12 description: The pediatric trial will test whether vaccinating young children is safe and effective canonical: https://time.com/5949859/pfizer-vaccine-children-under-12/ author: Alice Park article:opinion: false article:content_tier: free article:published_time: 2021-03-25T17:10:02.000Z article:modified_time: 2026-02-24T09:48:09.287Z article:section: Health og:title: Pfizer-BioNTech Start Testing COVID-19 Vaccine in Children Under 12 og:description: The pediatric trial will test whether vaccinating young children is safe and effective og:url: https://time.com/5949859/pfizer-vaccine-children-under-12/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt88e6147182cb3d9d/698a182d22fb85004ce2c08a/GettyImages-1231819007-e1616684312520.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 1600 og:image:height: 900 og:image:alt: US-HEALTH-VIRUS-VACCINE og:type: article twitter:card: summary_large_image twitter:title: Pfizer-BioNTech Start Testing COVID-19 Vaccine in Children Under 12 twitter:description: The pediatric trial will test whether vaccinating young children is safe and effective twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt88e6147182cb3d9d/698a182d22fb85004ce2c08a/GettyImages-1231819007-e1616684312520.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # Pfizer-BioNTech Have Started Testing Their COVID-19 Vaccine in Children Under 12 > Sponsored content. 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Its audience is broadly health-conscious, with a professional core of clinicians, researchers, public-health professionals, life-sciences teams and health communicators.  by [Alice Park](https://time.com/author/alice-park/)  ## Alice Park Senior Correspondent Mar 25, 2021 5:10 PM UTC  Registered Nurse Morgan James loads a syringe with a dose of the Pfizer Covid-19 vaccine at the Blood Bank of Alaska in Anchorage on March 19, 2021\. - Alaska became the first state in the country last week to open vaccination access to everyone over the age of 16 and has fully vaccinated 16 percent of the state's population, the highest rate in the country. (Photo by Frederic J. BROWN / AFP) (Photo by FREDERIC J. BROWN/AFP via Getty Images) Registered Nurse Morgan James loads a syringe with a dose of the Pfizer Covid-19 vaccine at the Blood Bank of Alaska in Anchorage on March 19, 2021\. - Alaska became the first state in the country last week to open vaccination access to everyone over the age of 16 and has fully vaccinated 16 percent of the state's population, the highest rate in the country. (Photo by Frederic J. BROWN / AFP) (Photo by FREDERIC J. BROWN/AFP via Getty Images) AFP/Getty Images  by [Alice Park](https://time.com/author/alice-park/)  ## Alice Park Senior Correspondent Mar 25, 2021 5:10 PM UTC Alejandra and Marisol Gerardo are nine years old but already making a little bit of history. The twin sisters are among the first young children to get vaccinated with a COVID-19 shot in Pfizer-BioNTech’s study of its vaccine in kids under age 12. Alejandra and Marisol had their blood drawn in the morning on March 24, then got their first dose of the two-dose vaccine later that afternoon at Duke University Medical Center, one of four study sites in the U.S. for the trial. “Their primary concern was, ‘is it going to hurt,’” says their father, Dr. Charles Gerardo, chief of emergency medicine at Duke University School of Medicine. “They’re not too worried about the long term side effects; they’re looking at the moment, not the future.” Testing the vaccine in younger children will answer critical questions about how much immunity the shots can provide, and potentially give parents and education officials more confidence in re-opening schools. While it appears that younger children don’t get as sick with COVID-19 as older teens and adults do, how these children’s immune systems respond to the virus, and to the vaccine, remains a black box. The trial will also help provide some clarity on those questions. Pfizer-BioNTech says it will test the same vaccine that is currently [authorized](https://time.com/5920134/first-authorized-covid-19-vaccine-us/) for emergency use in the U.S. for those 16 years and older, but this time in children aged six months to 11 years. The company is currently wrapping up a study of its two-dose shot in adolescents aged 12 to 15 years in the U.S. and Europe. The latest pediatric trial will follow the same three-phased approach as the adult study, with Phase 1 involving 144 children aged five to 11 years at Duke, Boston Children’s Hospital, Cincinnati Children’s Hospital and Johns Hopkins, who will all receive the vaccine but be randomly assigned one of three dosages. If the vaccine is safe in this age group, children aged two to four years will be tested, and if safe in that group, the youngest children from six months to two years will get the vaccine. Depending on the immune responses these children generate, the scientists at Pfizer-BioNTech will make a decision about the safest and most effective dose with which to proceed in its Phase 2 and Phase 3 studies. Those will include a total of about 4,500 children broken down in the same age categories, this time randomly assigned to receive either the vaccine or placebo in a 2:1 ratio. The results will be analyzed after six months to determine if the children receiving the vaccine both generated a stronger immune response than those getting placebo, and that the response was on par with responses in vaccinated adults. If that’s the case, then Pfizer-BioNTech will submit the data to the U.S. Food and Drug Administration to expand authorization to younger children, and hopefully start vaccinating them by early next year. Dr. Emmanuel Walter, professor of pediatrics and chief medical officer at the Duke Human Vaccine Institute who is overseeing the trial there, says the study will answer important questions about the safety and dosing of the vaccine for children—specifically whether younger children will need a different dose than adolescents and adults. The trial will test a dose about one-third that of the current adult dose, another that is about half of the adult dose, as well as the adult dose. While the Pfizer-BioNTech COVID-19 shot is the first mRNA technology-based vaccine of any kind to gain FDA authorization, Walter says it’s likely to be safe in children. “I don’t think it’s the platform so much that I would worry about for young children—I feel comfortable giving the mRNA to young children. I think the questions of will they have side effects, will the vaccine be tolerable to children, and do we need to use a smaller dose in young kids, are the biggest things.” So far, Walter says that they have seen an “overwhelming” response to the pediatric trial, with parents like the Gerardos expressing interest in enrolling their children. Both Gerardo and his wife, who is an infectious disease physician at Duke, are vaccinated, and he says before his daughters joined the trial, they discussed volunteering with the girls. “They understand that the results are going to impact other kids, and that’s one of the lessons we wanted to teach them with this experience,” he says. “That this was one of the ways to contribute to help other people.” ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/5949859/pfizer-vaccine-children-under-12/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/5949859/pfizer-vaccine-children-under-12/"},"headline":"Pfizer-BioNTech Have Started Testing Their COVID-19 Vaccine in Children Under 12","datePublished":"2021-03-25T17:10:02.000Z","dateModified":"2026-02-24T09:48:09.287Z","description":"The pediatric trial will test whether vaccinating young children is safe and effective","url":"https://time.com/5949859/pfizer-vaccine-children-under-12/","keywords":["COVID-19"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/blt88e6147182cb3d9d/698a182d22fb85004ce2c08a/GettyImages-1231819007-e1616684312520.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"Alice Park","jobTitle":"Senior Correspondent","url":"https://time.com/author/alice-park/"}],"articleSection":"Health","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/blt88e6147182cb3d9d/698a182d22fb85004ce2c08a/GettyImages-1231819007-e1616684312520.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"US-HEALTH-VIRUS-VACCINE","caption":"US-HEALTH-VIRUS-VACCINE","creditText":"AFP/Getty Images","representativeOfPage":true}],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/covid-19/","name":"COVID-19"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/5949859/pfizer-vaccine-children-under-12/","name":"Pfizer-BioNTech Have Started Testing Their COVID-19 Vaccine in Children Under 12"}}]}] ```