An advisory group unanimously recommended that the Moderna and Pfizer vaccines be approved for the youngest children.


In the United States, children under the age of five are now the last age group to receive the COVID vaccine.

The Pfizer-BioNTech vaccine was approved by a Food and Drug Administration advisory committee by a vote of 21 to 0 for children aged six months to four years, and the Moderna vaccine was approved by a vote of six months to five years. The conclusion of the FDA's Vaccinations and Related Biological Products Advisory Committee indicates a consensus among health experts on the panel that the vaccines' benefits outweigh the dangers for the youngest children.

Based on its own analyses, the FDA determined that both Moderna's and Pfizer's vaccines were safe for these age groups and met its efficacy standards based on immunological response.

If the government follows the advisory committee's recommendations and the US Centers for Disease Control and Prevention approves the vaccinations, they might be available to these children soon.

"This was a momentous day for parents who want to know that they have another approach to protect their child," says FDA vaccine advisory committee member Paul Offit, director of the Vaccine Education Center and attending physician at Children's Hospital of Philadelphia's division of infectious diseases. He compares the young children's wait for the vaccine to a scene from the film Jaws, in which a character describes a group of Navy sailors stranded in shark-infested waters and waiting for a helicopter to rescue them. "The worst part was waiting for your turn while the helicopters were saving people," Offit adds, quoting the line.

Sallie Permar, chair of pediatrics at Weill Cornell Medicine and pediatrician-in-chief at New York–Presbyterian Komansky Children's Hospital, says, "As doctors, being able to deliver this lifesaving invention to our kids has been top of mind." "Not only are you preventing your child from developing a serious illness, but you're also assisting them in achieving the normalcy in life that we've all been seeking—to continue with your existing activities without interruption."

In December 2020, the first COVID vaccines were given emergency use authorisation (EUA) for adults, and Pfizer's vaccine's EUA was later amended to include those aged 16 and up. Pfizer's vaccine became accessible to 12- to 15-year-olds in May 2021, and to 5- to 11-year-olds in October of last year.

Despite the notion that COVID is less likely to cause serious disease in children than it is in adults, 442 children under the age of five had died in the United States as of June 2. (In the 2019–2020 season, influenza claimed the lives of 87 children in this age range.) Many more children have been admitted to hospitals with COVID, particularly since the current Omicron outbreak. Multisystem inflammatory syndrome in children (MIS-C) is a disorder that causes inflammation in organs such as the heart, lungs, kidneys, and brain in children. Children, like adults, can be affected by lengthy COVID.

It's usually difficult to test a new vaccination in youngsters because the required safety threshold is higher in a population of people who are still developing and are normally healthy. Furthermore, COVID poses the greatest risk of serious disease and death in older persons. As a result, it made logical to begin testing vaccines in the later age group first when they were produced.

Offit explains, "We worked our way down." Because older folks account for the great majority of COVID deaths, health officials wanted to make sure they were the first to receive the immunizations. They were next tested on young adults, then five to eleven-year-olds, and finally children under the age of five. "At the very least, parents can rest certain that there have been billions of doses out there," he says. "At this time, you have a lot of knowledge on these vaccines."

Because young children have a minimal probability of being really ill as a result of COVID, makers and authorities wanted to ensure that the vaccination did not have any side effects that were more dangerous than the disease itself. Pfizer tested two child-specific doses of their vaccine, each one tenth of an adult dose, for children under the age of five, but this did not induce a robust enough immune response, so a third dose was added. Moderna tested two doses of its vaccine, each a quarter of an adult dose, in children under the age of six.


Mild to severe adverse effects were common in both the Pfizer and Moderna vaccination studies, with the most common being pain and redness at the injection site, headache, weariness, irritability, and fever. Except for fever, which is extremely dangerous in babies because it can cause seizures, all were milder and less frequent than in older children and adults. A tiny percentage of trial participants experienced a seizure or other adverse event, but the majority of these were determined to be unconnected to the vaccination.

In neither trial, there were any occurrences of myocarditis or pericarditis (inflammation of the heart muscle or its lining) among children aged six months to four or five years. There have been a few cases of vaccine-induced myocarditis or pericarditis in older teens and young adults, mostly males, although these cases were mostly self-resolving. Inflammation caused by COVID and other illnesses is typically more severe than that caused by vaccinations. In the trials, there were no deaths among the children.


Both the Pfizer and Moderna vaccines produced immune responses in young children that met the FDA's criteria for approval. Immunobridging was used to measure their efficacy, which involved comparing the levels of vaccine-elicited antibodies that neutralize the virus that causes COVID in young children to the levels in young adults.

Three doses of the Pfizer vaccine had an apparent efficiency of 80.4 percent in preventing proven COVID in children under the age of five, according to a preliminary investigation (75.6 percent in six- to 23-month-olds and 82.4 percent in two- to four-year-olds). The apparent efficacy of Moderna's two-dose vaccine was 50.6 percent in children aged six to 23 months and 36.8 percent in children aged two to five years.

Although these efficacy rates are lower than those seen in older children and adults, it should be noted that the vaccine trials in young children took place at a time when the relatively new Omicron variant was already circulating, which is known to partially evade immunity from vaccination or previous infection.

"A significant distinction here is that the virus has changed," adds Permar. "The virus that's currently circulating is the Omicron form, which we know is more transmissible than any of the other variants and can bypass vaccine immunity evoked by the original-strain vaccine," says the researcher. She claims that the vaccinations' efficacy in young children matches real-world evidence for adults with the Omicron version. "It's almost like the game changed when the trials for the youngest children were completed," she adds.

Kawsar Talaat, an associate professor of international health at Johns Hopkins Bloomberg School of Public Health and a researcher in a Pfizer vaccination study in children, agrees. "It's definitely unfair to compare... this vaccination as tested in little children during the Omicron period to the same vaccine as tested in adults," she says.

In adults, the immunizations continue to provide good protection against serious disease, hospitalization, and death, and children should receive similar protection.

There are now two vaccines available for young children that have very similar processes but differ in dosages, dosing intervals, and efficacies. Talaat is interested to see if the CDC will favor one vaccine over the other. "I'd rather have a more effective one for my kids, even if it takes longer," she adds, adding that this is "a dialogue people should have with their GPs, if we have the fortune of having a choice."

Frustration and relief

Many parents are anxious to get their newborns and young children immunized. Many of those Scientific American spoke with expressed relief, followed by dissatisfaction at the length of time it took for authorization to be granted.

Fred Blau has a five-year-old daughter and a three-year-old boy in Brooklyn. "Both my wife and I am strongly provaccination," he says. "We were hoping to get our kids vaccinated in the fall or winter of 2021, or even in January of this year," she said, "but we were waiting and waiting and waiting." Despite the fact that his son has experienced COVID, Blau believes it is still important to get him vaccinated. "Although young children are more likely to have the least severe sickness, there are still hazards, and we'd like to minimize them as much as possible so that we can return to our normal lives," Blau adds.

Sarah Trist of Albany, California, has a five-year-old boy and a 22-month-old daughter. She works at the City of Oakland's Head Start program, which provides early childhood education, and she has witnessed directly how COVID can wreak havoc on a daycare center. "Every day, I wait for the call from daycare informing me that my child has been confined," she adds. She was optimistic when the immunizations were originally released, but "the finish line just kept moving," with one delay after another. Trist describes the feeling as "very bittersweet" now that the day has arrived.

"The main sense is relief," says Allison Moy, a Pittsburgh-based mother of a 20-month-old son. "A lot of people kind of went back to life as usual once vaccines for adults and older kids came out," says Moy, a microbiologist. "However, we couldn't do it since we needed to think about our child." When her son's pediatrician emailed parents to schedule vaccine appointments before the authorisation announcement, Moy immediately called and made an appointment. "I don't care!" she said when she was given the option of working for Pfizer or Moderna.

However, not all parents share this enthusiasm. In the United States, fewer than 60% of children and teenagers aged 12 to 17 are fully vaccinated, and fewer than a third of children aged five to 11 are fully vaccinated. Only roughly one in five parents of children under the age of five said they want their child vaccinated "very away," according to a Kaiser Family Foundation study, while another two in five said they want to "wait and see" how the vaccine works. Nearly a third of parents with children that age indicated they would "absolutely not" get their children vaccinated.

"As long as people don't believe this is a serious infection in children, particularly young children," Talaat says, "they are reluctant to get their child vaccinated." "Inadvertently, leaving the youngest kids to last in the trials has signalled to parents that it isn't that necessary," Permar adds. Permar says that scientists need to reconsider how they perform clinical studies in children. While it's critical to do early tests of novel medical products in consenting adults, she believes that young children should be involved earlier in the process.

However, for parents like Trist, the data on vaccine safety is sufficient. She claims that any risk from the vaccine is "far smaller" than the chance of COVID, and that "it's a pretty simple option to make."