Dr. Cassandra Scott, a pediatrics and psychiatry resident at Tufts Medical Center, enrolled her 9-month-old baby in a COVID-19 vaccine trial after learning about the opportunity from her clinic supervisor.

“It was almost a no-brainer for me to sign her up,” Scott said.

Despite never being part of a vaccine trial before, and not knowing anyone who had been part of one, Scott was confident that she wanted her baby to participate. As someone who worked in a hospital 70 hours a week, she hoped to lessen the risk of exposing her infant to the virus. And since her clinic supervisor is one of the trial’s principal investigators, she trusted the process and the people in charge of it.

Her baby is now 13 months old, healthy, and a participant in Moderna’s KidCOVE vaccine trial.

Not all parents share Scott’s confidence in the vaccine testing process for kids, and understandably so. Most people don’t know much about vaccine trials besides the fact that they involve injecting a drug that has not yet been authorized for general use into the body. 

Many parents are also nervous about immunizing their child once a vaccine is authorized for their kid’s age group. The Pfizer vaccine for kids ages 5 to 11 was authorized back in late October, but months later, nearly half of parents of kids in this age group say they will either “definitely not” get their kid vaccinated or only do so if required. This hesitancy helps explain why COVID-19 immunization rates among children remain low—only 28 percent of kids 5 to 11 have been vaccinated. 

Many hesitant parents say they don’t have enough information about the COVID-19 vaccines or that not enough research on them has been done. For people who are not familiar with how vaccines are tested and made, COVID-19 vaccines may seem experimental or unsafe because of their rapid development. But the technology used in these shots has been in development for decades. Even the vaccine candidates used in trials are not nearly as “untested” as the general public may think.

Before the trial begins

There are several checkpoints a vaccine candidate must pass before it can even be considered for kids. First, it goes through years of basic laboratory research. Scientists had been studying and working with mRNA vaccine technology for decades prior to the creation of the Pfizer-BioNTech and Moderna COVID-19 vaccines.

Second, a vaccine must pass the preclinical stage, during which it is tested in nonhuman beings, such as cell systems and animals. Due to the urgent nature of the COVID-19 pandemic, rather than waiting for results from the preclinical trial, both Pfizer and Moderna received approval to run animal testing and early trials on humans at the same time.

When testing in humans, clinical trials begin with a small population of healthy adults. Once the vaccine is proven to be safe in this phase of the trial, it is then expanded to other age groups and specific populations. The trials are conducted in a total of three phases, enrolling tens of thousands of people, to collect data on whether the vaccine works.

Moderna and Pfizer launched the first phase of their trials in March and April 2020, respectively. The second and third phases, which were combined to speed up the process, began about three months later; that’s when kids ages 12 and older became involved. 

Testing in kids under 12 took place in a separate set of trials that started in March 2021, several months after vaccines for adults had been authorized and administered. This is because a much lower dose was tested in this younger age group. 

Ruth López, an education professor at the University of Houston, started looking into vaccine trials because her then 8-year-old son has a history of asthma, making her especially worried about the adverse symptoms he could experience if he were to get COVID-19. For López, understanding the ways a vaccine is evaluated prior to being tested in kids made her more comfortable with the idea of enrolling her son in Moderna’s KidCOVE study.

“It helped that both the Pfizer and the Moderna vaccine for adults were approved at that time,” she said. “That really helped to temper any fears.”

She also attributed her confidence in the vaccine trial to the information she received from the principal investigator and research staff. They made sure not only that she had read the required documents and was fully informed, but also that her son, who is now 9 years old, understood the process and agreed to be a part of it. 

“They talk to both of you when you come in and are really good about checking with the child for understanding,” López said. “They really try to ensure the autonomy of the child to be able to decide something like this.” 

Dr. Erin Nicholson, the principal investigator who led the trial López’s son was a part of, said she typically spends about an hour going through the consent form with parents and making sure they are comfortable with everything.

If a child is 7 or older, both the parent and the child have to give their approval in order to participate. The clinical team explains the trial in language that kids can understand and gives the children the power to say no to participating, even if their parents give the go-ahead.

The team also makes clear the commitment required to be in the study, which typically lasts at least a year, though participants have the right to drop out at any time. To account for the time, effort, and resources participants will have to spend on office visits, journal keeping, phone check-ups, and more, clinical trials typically offer some compensation.

During the trial

A strict monitoring process begins immediately following the first dose. Parents are responsible for measuring potential redness and swelling at the injection spot, taking their kid’s temperature, and keeping detailed reports of their child’s condition in online diary entries. The clinical team checks in through routine telehealth calls and in-person visits. Parents are also required to report any potential exposure or symptoms of infection.

Nicholson said the close monitoring process is critical for collecting data and ensuring safety. This communication goes both ways. When news came out that there was the rare possibility of experiencing myocarditis—a type of heart inflammation—after receiving the vaccine, Nicholson’s team immediately reached out to trial participants to make sure they were aware of the new finding.

The clinical team is also accessible if any concerns arise from children or parents. Ari Kohen, a political philosophy professor at the University of Nebraska–Lincoln, enrolled his 4-year-old son in the Moderna trial in fall 2021. He said a major benefit of being in the trial is the abundance of support from the clinical staff.

“If your kid has symptoms or if they’re not feeling well, you just call the clinic and they’ve got pediatricians on staff to answer all kinds of questions and give you advice on all kinds of things,” Kohen said. “We have a phenomenal relationship with our pediatrician, but since being a part of the trial, all of a sudden we have four pediatricians.”

Depending on the phase of the trial, participants may have a chance of receiving a placebo rather than the actual vaccine. This process is “blinded,” meaning participants don’t know whether they’re getting the real shot or not until a set future time, an element of uncertainty that can be frustrating for those who entered the trial with the goal of being immunized as soon as possible. Still, participants say any chance of receiving the vaccine is better than none. Being part of a process that helps others is often also a motivating factor.

Kohen’s 4-year-old was part of the blinded phase of the study, so even after he got his first shot, his family continued to make decisions based on the assumption that he had not yet been vaccinated. He was unblinded from the study when he turned 5 in March and would have been eligible for the Pfizer vaccine. 

“On his birthday, when he found out he got the shot and was fully vaccinated, he was super excited,” Kohen said. “It was very cool. Now, the only reason we continue to take precautions is because COVID is still very disruptive to people’s lives. We’re still doing things that are designed to keep the kids in school every day and keep us healthy and at work.”

The decision to participate

After Scott posted a photo on Twitter of her baby receiving the first shot of the Moderna vaccine, she was taken aback by some of the messages she received. They ranged from “I’m praying for your child” and “Your child isn’t a guinea pig” to claims that she was using her baby as a pawn for attention. But the majority of responses Scott received were positive, thanking her for involving her family in the process.

Her primary reason for placing her child in the vaccine trial was a desire to protect her baby. Scott assumes the same motivations of her patients’ parents.

“When I talk about vaccines with parents, I really operate on the assumption that everyone is trying to do what’s best for their kid and nobody has any bad intention toward their children,” Scott said.

But the lack of awareness and transparency around COVID-19 vaccines can pose a barrier to parents hoping to make the best, most informed decision for their child. The amount of misinformation circulating about vaccines for kids can add to the confusion and turn healthy caution into ingrained false beliefs. 

Scott, López, and Kohen all benefited from being connected to health professionals who they trusted and could rely on for answers to their questions and concerns. This access to reliable information influenced not just their decision to enroll their kids in a vaccine trial, but also their general confidence in medicine and science.

“The more information people have, hopefully the more people will start to embrace the idea again that we can do remarkable things with science,” Kohen said. “None of this needs to be a mystery.”

Correction: May 13, 2022
An earlier version of this article misstated the age of Ruth Lopez’s son. He is 9 years old as of publication, not 8.