While drug companies and governments around the world are in an all-out sprint to develop a coronavirus vaccine for adults, the race to identify one that is safe and effective for children lags far behind, meaning America's youngest may not be vaccinated until late next year, health experts told ABC News.
Despite recent evidence that children may play a larger role in the community spread of COVID-19, experts say the delay is appropriate, because a vaccine should be tested in adults first to ensure it's safe and effective before being tested in children.
“We wouldn't start injecting five-year-olds before we knew what this vaccine did in adults,” said Dr. William Schaffner, professor of preventive medicine and infectious diseases at the Vanderbilt University School of Medicine in Nashville.
“Kids are not little adults, they have very different immune systems, and you might need to have a completely different kind of vaccine for kids,” said Dr. Anita McElroy, a pediatric infectious disease physician at the University of Pittsburgh Medical Center. "And we're just so at this point so far behind the power curve, we're at the very beginning of any kind of vaccine against COVID [so] that to think we could just take one that works in adults and put it in kids and assume it's going to work fine is actually a foolish thing to do.”
Dr. John Brownstein, epidemiologist, Boston Children’s Hospital and ABC News contributor, said there are simply "a lot of things we have to understand" from dosage to learning from safety studies, "so those take time before you can start ramping up and looking at a broader population of kids."
Still, in a letter to federal health officials this week, the American Academy of Pediatrics called for the inclusion of children in research on potential COVID-19 vaccines, saying that "beyond the direct impact of infection, children have been greatly affected by the pandemic."
"Children must be included in vaccine trials to best understand any potential immune responses and/or unique safety concerns," AAP President Dr. Sally Goza wrote.
Dr. Steven Joffe, a professor of medical ethics and health policy at the University of Pennsylvania, said that currently, "none of the major trials in the U.S. are enrolling kids." The exception is Pfizer, which recently announced it would expand its trials but only to enroll 16- and 17-year-olds.
MORE: World Health Organization announces distribution plan for COVID-19 vaccineThree vaccine groups told ABC News that they plan to schedule pediatric trials once the vaccine for adults is rolled out. Dr. Fauci, the nation’s leading expert on infectious diseases, said in an interview with WTOP in mid-September that adults who are in the high-risk category could be getting a vaccine in December or at the beginning of the year.
Johnson & Johnson, one of the groups that entered the late-stage trial testing its adult coronavirus vaccine, is planning to include studies evaluating children, but will only move forward after data from adults is analyzed, according to a spokesperson for the company.
Moderna, a Massachusetts based biotechnology company, is hoping to start trials that include children as soon as the end of the year.
“Moderna shares the urgency associated with assessing COVID-19 vaccine candidates in children,” a spokesperson for the company said in a statement. “Now that Moderna has sufficient safety data in adults, we intend to start pediatric trials by the end of this year, subject to regulatory approval.”
Likewise, a spokesperson for Inovio Pharmaceuticals, a biotechnology company, told ABC News that “it’s broadly industry standard to begin trials in the adult population and then schedule pediatric trials once safety has been established.”
Some other leading drug companies in the race for an adult vaccine did not respond to ABC News' request for comment about their efforts regarding children.
Brownstein said another complication is the recruitment process for clinical trials for kids, which is more difficult because parents or guardians need to consent to participate in the studies.
“The reality is that trials for kids have yet to be started,” said Brownstein. "Those will be in the coming year and so it will be at least a year before we start seeing COVID vaccines in our kids.”
Brownstein emphasized that clinical trials for children need to focus on "diverse populations" and said efforts "need to account for the clear disparities in health outcomes when it comes to COVID-19" -- so as not to repeat what's already been a challenge when it comes to adult trials.
MORE: As vaccines move into phase 3 trials, diversity must be at top of agendaIn her letter, Goza noted that more than two-thirds of the over 100 children who have died after being infected with COVID-19 were Black or Latino.
This delayed rollout of a pediatric vaccine means parents everywhere are brimming with uncertainty about what the next few years could look like, particularly for schools.
Although fewer children have been sick with COVID-19 compared to adults, the CDC notes that some children can get severely ill from COVID-19. They might require intensive care, hospitalizations and in rare cases, they could die.
According to data from the American Academy of Pediatrics and the Children’s Hospital Association, over 624,000 children have tested positive for COVID-19 since the onset of the pandemic.
“We are now over 100 deaths in children from COVID-19 in the past seven months. This is around 15 deaths in the U.S. every month,” said Dr. Evan Anderson, professor of medicine and pediatrics at Emory University School of Medicine and pediatric infectious disease specialist at Children’s Healthcare of Atlanta. “It is very important that we start these clinical trials in children now to provide critical answers that will be needed to advance a vaccine or vaccines toward licensure that can prevent pediatric hospitalizations and deaths.”
Beyond concerns for the health of children themselves, a vaccine for kids could be an effective weapon in the ongoing fight to stem the spread of the virus, experts said.
MORE: COVID-19 cases rising among US children as schools reopenOn Tuesday, the American Academy of Pediatrics and the Children's Hospital Association published a study that showed that the number of children infected with COVID-19 increased from April to September. According to the study, in April, children accounted for about 2.2% of all reported U.S. cases, but by September, that figure had risen to 10%.
“While children do not play the same role in transmission with this virus like with influenza, they do play a role in transmission,” said Dr. Sean O’Leary, vice chair of the AAP Committee on Infectious Diseases. “We certainly know that children can get it and can spread it. And so I think there is certainly urgency across the board for children to get a safe and effective vaccine.”
Anderson said he believed that if "efforts were made to begin in earnest pediatric vaccine studies now of advanced COVID-19 vaccines, we might have a vaccine licensed by the start of next school year."
Dr. Anna Durbin, a professor at the John Hopkins Bloomberg School of Public Health, predicts that if everything goes perfectly, the U.S. might have a vaccine ready for children by June 2021. But Durbin cautioned another reason it might be harder to conduct vaccine studies for children than it has been for adults: lower incidence of symptomatic COVID-19 in children means the trials might need to be even bigger than those for adults to demonstrate the vaccine works.
“This is critical as without advancing a vaccine, we can anticipate ongoing school closures, outbreaks, and hospitalizations and even deaths due to COVID-19 in children," Anderson said.
Dr. Sallie Permar, a pediatric immunologist at the Duke University School of Medicine, said that a vaccine would help schools “operate without having all the complexities that come with trying to run a school in the middle of a pandemic.”
When a coronavirus vaccine for children is rolled out, Linda Mendonca, the President of the National Association of School Nurses, said she is hoping school clinics receive them first.
“Parents trust school nurses and by providing a vaccine in school-based clinics, it removes some of those barriers for families,” Mendonca told ABC News. “The vaccine is important for everyone but when you’re looking at bringing children into schools, it should be thought of as a priority.”
But for now, Brownstein said that it's likely to be quite a while before that vaccine arrives, as urgent as the need is.
“Children deserve the same level of prioritization,” he said. “I mean, clearly we want to focus on those that are going to have the most severe impacts of the virus, but children are still critical and especially as we're trying to keep kids in school and bring them back to a normal life, having a vaccine is so important for that return to normal.”
According to Vanderbilt's Schaffner, for the time being, the burden of protecting children from coronavirus will fall not on a vaccine, but on the adults' behavior.
"If the adults in the community would accept the vaccine, we can immunize the teachers, the entire staff, all the parents, everybody in that community that will immediately reduce the risk to children enormously," he said. "That will be a big benefit.”
ABC News' Sony Salzman and Ramie Fathy contributed to this report.