Pfizer and BioNTech said Thursday they are beginning a study aimed at showing their Covid-19 vaccine can be used in children as young as 6 months.
The study follows the launch of a separate and ongoing trial in children ages 12 to 15, which was fully enrolled in January. That study could lead to results by the end of the first half of the year, depending on the data, and then to an emergency use authorization. That will depend on the Food and Drug Administration and the Centers for Disease Control and Prevention. The vaccine already has an EUA for people 16 and older.
“The FDA, if it sees fit to do this, could, grant an EUA and get them into children in that age group by the fall, provided the CDC also agrees and that that should be the vaccine they receive,” said William Gruber, Pfizer’s senior vice president of vaccine clinical research and development.
Results in younger children would not be expected before the second half of the year, meaning that they could be eligible to receive the vaccine sometime early next year.
Pfizer also expects to file a biologics license application, the application for a full FDA approval, for its vaccine during the first half of 2021, based on additional data from the study that resulted in the vaccine’s initial authorization.
The new study will initially test three different doses of the vaccine in small groups of children to measure side effects and the ability of the doses to produce antibodies against the SARS-CoV-2 virus, which causes Covid-19. That part of the study will include 144 participants ranging from 6 months to 12 years.
After that, the companies will pick doses in each age group and test them in 4,500 volunteers. Two volunteers will be randomly assigned to receive the vaccine for each that receives placebo. After six months, all participants will receive the vaccine.
It probably won’t be possible, based on that number of patients and the number of children and adolescents who are likely to develop Covid-19 in the study, to prove that the vaccine reduces the risk of symptomatic infection in these age ranges. Instead, Pfizer plans what is known as a bridging study to show that antibody levels from the vaccine are similar to those seen in adults.
Researchers will also be monitoring side effects. Younger people are more likely than older adults to have side effects like fever from the vaccine as their immune systems ramp up in response to the inoculation, creating defenses against Covid-19.
But Gruber said that based on the company’s experience with adolescents, children might not be more likely to get fevers, headaches, and other expected vaccine side effects, which are not dangerous but can be very uncomfortable.
“We’re encouraged by the blinded data that we’ve seen for the 12- to 15-year-olds,” Gruber said. “That looks very similar to what we saw in 18- to 25-year-olds. We’re now going to move judiciously down to 5 to 11. But instead of picking the adult dose, because now we’re getting into a range where we might be more likely to see some increased fever at that dose and perhaps other reactions, we’re going to start at a lower dose.”
Moderna, whose Covid-19 vaccine is authorized for people older than 18, has also started a pediatric study.
Overall, Gruber said, it is hoped that if SARS-CoV-2 becomes a lasting presence in our lives, as many experts expect, the process of creating and testing new vaccines will become faster. He said the FDA is clearly looking at a “future state” in which producing shots for new variants of shots for Covid-19 will be much like producing new influenza vaccines each year.
“If we have to chase a new variant of concern for which we really think there’s little likelihood of protection [from the existing vaccine], it could be like introducing new flu strain each year,” Gruber said. Eventually, he hopes, there will be enough confidence in the approach that new clinical trials won’t be required each time. “And we don’t have to study anybody, frankly, any more. We just reckon that the experience with the platform is such that we can reliably predict that manufacturing that product will provide protection.”