Encouraging news about COVID-19 vaccines keeps coming. No unusual safety issues arose during the first month of vaccination, when 13.8 million doses of the Pfizer and Moderna vaccines were administered in the United States, the U.S. Centers for Disease Control and Prevention reported February 19. The vaccines also appear to slow the spread of the coronavirus (SN: 2/12/21).
But the available data on COVID-19 vaccines — as well as access to them — centers almost entirely on adults. Most children aren’t yet authorized to receive the shots. An exception is 16- and 17-year-olds; last year, Pfizer expanded its adult trial to these older teens. They were included in Pfizer’s emergency use authorization in the United States, although few have actually been vaccinated, as the group isn’t prioritized to get the shots yet. The World Health Organization also recommended emergency use of this vaccine for 16- and 17-year-olds.
The work to fill in the data gap on kids and COVID-19 vaccines is now gaining steam. Pfizer is testing their vaccine in adolescents as young as age 12. Moderna is currently recruiting for a clinical trial for 12- to 17-year-olds. And on February 12, AstraZeneca announced the start of a trial for their jab in children ages 6 to 17.
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As to when a COVID-19 vaccine might get the OK for use in adolescents in the United States, “I’d be optimistic for summer,” says infectious disease physician Emily Erbelding, who directs the Division of Microbiology and Infectious Diseases at the National Institute of Allergy and Infectious Diseases in Rockville, Md. It would most likely be Pfizer’s vaccine, as the company is the farthest along with testing in adolescents. Younger children will wait longer for a COVID-19 vaccine, with most trials not yet under way for those under 12 years old.
Getting past the pandemic
Proving the shots are safe and effective for children is a crucial first step to vaccinating this population and protecting kids’ health. Although severe illness from COVID-19 is much less common in children than adults, kids haven’t come out unscathed. More than 3 million cases of COVID-19 have been reported in children in the United States, according to the American Academy of Pediatrics. Black and Latino children have a disproportionate share of SARS-CoV-2 infections, researchers reported in Pediatrics in October 2020.
There have also been more than 2,000 cases of multisystem inflammatory syndrome in children, or MIS-C (SN: 6/3/20), a rare but serious complication of a SARS-CoV-2 infection. The brunt of these cases have been among Black and Latino children. And indirect harms from the pandemic continue to mount, as disruptions to children’s education and social lives endanger their health.
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Furthermore, getting children immunized is part of how society gets past the pandemic. In the United States, there are around 73 million children. “In order to reach a level of herd immunity in our population where we can get rid of this virus, we’re going to need to vaccinate our kids,” says Kawsar Talaat, a vaccine researcher and infectious disease physician at Johns Hopkins University Bloomberg School of Public Health.
Along with establishing herd immunity, vaccinating children is necessary to curb the emergence of more variants (SN: 2/5/21). “If you fail to vaccinate a population … that means you’re still allowing the virus to go on to have new mutations” as it continues to spread, says pediatric infectious disease doctor Sharon Nachman at the Stony Brook University Renaissance School of Medicine in New York.
Testing in children
To pave the way for children to be vaccinated against COVID-19, the shots will be tested in this group to assess effectiveness, safety and dosing. The trials will proceed somewhat differently for younger individuals than for adults.
To measure how well the shots worked for adults, clinical trials assessed whether the vaccines prevented symptomatic illness. That required tens of thousands of participants, so there would be enough cases of symptomatic COVID-19 to compare cases among those who had and had not gotten vaccinated and determine the vaccines’ efficacy (SN: 10/4/20).
But to do this for children, trials “would have to even be larger,” says Erbelding, because symptoms are less likely to occur in children than in adults. Instead, researchers will look at how children’s immune systems respond to the vaccine, by measuring antibodies, for example. With data from adults’ immune responses as a guide, the trials can assess whether the vaccines work for children.
The trials for children will also monitor vaccine safety. The fact that the shots have proven safe in adults — both in testing and post-vaccination monitoring — is a good sign, as there isn’t reason to expect wildly different reactions in children than in adults. Some researchers have wondered if MIS-C is a risk after vaccination, as children diagnosed with the syndrome have higher levels of antibodies than children with COVID-19. However, a similar form of this complication in adults, MIS-A, has not been reported in adults who have been immunized. “That should lend some reassurance,” says Erbelding.
When figuring out dosing, the goal is “to see what gets you into the sweet spot of good immune response” and manageable side effects from the shot, says Nachman. Some of the expected side effects with COVID-19 vaccines are pain at the injection site, headache and fatigue. Adolescent trial participants are receiving the same dose as adults. But younger children are smaller, and their immune systems tend to respond really well to vaccines, so there may be a different “sweet spot” for them. Vaccine trials for children are designed to test smaller doses as needed when moving into the ages of 7 to 11, 2 to 6 and under 2 years old.
It’s still a big question as to how many children might be able to be vaccinated before the start of the next school year. But it’s going to take getting everyone vaccinated to stop the virus so children “can go back to school in a normal fashion — without masks, without having to social distance, without all of the things that we’ve enacted in the last year,” says Talaat.
