Low dose of Pfizer-BioNTech vaccine is safe and effective in children ages 5 to 11, companies study finds

The finding, eagerly anticipated by many parents and pediatricians, is a crucial step toward the two-shot coronavirus vaccine regimen becoming available for younger school-aged children, perhaps close to Halloween.

The highly transmissible delta variant has collided with school reopening to reveal why children could benefit from a vaccine. Nearly 30 percent of cases in the first week of September were among children, according to the American Academy of Pediatrics. Although children rarely suffer severe illness, when they do it can be devastating. A vaccine could protect against rare cases of severe illness, cut the risk of long-haul covid and tamp down outbreaks.

The companies still must prepare and submit the data to the Food and Drug Administration, a process they expect to complete by the end of September. Then, the full data - which is not yet published or peer reviewed - will be scrutinized by regulators to ascertain that the vaccine is safe and effective. That could take weeks, or up to a month.

Sharon Nachman, a pediatric infectious-disease specialist at Stony Brook Medicine in New York, said a vaccine for children would be a "huge, huge step forward" and that she is "cautiously optimistic" about Monday's announcement.

"As most physicians are, I'm very cautious when it comes to the health of children," Nachman said. "I think it will be critical to have the data presented to a group of experts who are unbiased and have no conflicts of interest."

Regulators have made clear they are working as fast as possible, but also need to ensure the vaccine meets the highest standards - especially because a rare but concerning vaccine side effect of heart muscle inflammation has been identified, most frequently in the younger males eligible for the vaccines. An FDA analysis estimated that among 16- to 17- year old males, the risk was close to 1 in 5,000.

"You need to do these kind of studies, and it's going to be important to vaccinate children," said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. He called the results - that the vaccine triggered a robust immune response in children - somewhat predictable, but important.

With the school year in full swing and cases soaring among children, pediatricians have been inundated with requests to bend the rules and give children a shot now. The new data seems likely to intensify the pressure, even though the existing vaccine is triple the dose tested in the trial. Younger children's immune systems are not the same as adults, and the companies tested and found a much smaller dose was safe and effective.

Evan Anderson, a professor of pediatrics at Emory University School of Medicine in Atlanta, said the pediatric trials at his institution had to turn away many families, with 10 times as many people who wanted to participate as they had slots available.

"Parents kind of recognize that their children going off to school is a significant issue for them: The lack of ability to control their exposure, whether in the lunch room or the classroom," Anderson said.

But experts, including a Pfizer scientist, agreed that parents should be patient for regulators to pore over the details instead of seeking out doses on their own.

"No one should really be freelancing - they should wait for the appropriate approval and recommendations to decide how best to manage their own children's circumstances," said William C. Gruber, Pfizer's senior vice president of vaccine clinical research and development, who explained that younger children tend to have more "exuberant" immune responses than older people, both to this vaccine and others.

"Nature has equipped us, particularly when we are young, to respond very well to an assortment of things we will encounter in nature - and we will use vaccines to accelerate that process and really improve on nature," Gruber said.

Detailed data from the study in school-aged children was not immediately released Monday.

"Until we look at the data, I can't comment on this, other than to say: We need a vaccine for children," said Paul Offit, a vaccine expert at Children's Hospital of Philadelphia who serves on the expert committee that advises the FDA.

The step forward for a children's vaccine may deepen the rift between families eager for the vaccine and parents who are hesitant. Hospitalizations among children have increased in the delta surge, but children have been far less likely to develop severe illness and death than older people throughout the pandemic, leading to a perception among some that the disease is not harmful to them.

Among 12- to 17-year-olds eligible for the Pfizer-BioNTech shot since May, only about half have received at least one dose, according to the American Academy of Pediatrics. More than 5 million cases of covid-19, the illness caused by the coronavirus, have been reported among children and teens, causing 460 deaths since the start of the pandemic. There have been 20,000 hospitalizations among 24 states and New York City. Many families and schools have been navigating disruptive quarantines and at times divisive policies on use of masks.

"We are eager to extend the protection afforded by the vaccine to this younger population, subject to regulatory approval, especially as we track the spread of the Delta variant and the substantial threat it poses to children," Pfizer chief executive Albert Bourla said in a statement. "Since July, pediatric cases of COVID-19 have risen by about 240 percent in the U.S. - underscoring the public health need for vaccination."

In July, the FDA asked Pfizer and Moderna to increase the size of their children's trials to ensure the safety database was robust. There were nearly 2,300 children between ages 5 and 11 in Pfizer's trial, two-thirds of whom received the vaccine. The rest received saltwater shots.

The trial showed that children who received the vaccine had equivalent immune responses to teens and young adults who were protected, according to the companies. Two shots of a 10 microgram dose, spaced three weeks apart, were well-tolerated, with side effects similar to young adults.

Gruber said there appeared to be less fever and fewer chills among younger children than in a comparison group of 16- to 25-year-olds, increasing the companies' confidence they had found the right dose. There were no cases of myocarditis - the heart inflammation condition - in the trial, but because it is a rare event, it may only show up in monitoring as the vaccine is used in larger numbers.

Pfizer and BioNTech are seeking emergency use authorization as they continue to accumulate data to support an application for full approval in children.

Data on children younger than 5 is expected by the end of the year. Moderna is also conducting a trial with children as young as six months.

The urgency for the littlest children is just as great, in part because they may not be old enough to wear masks, or may struggle to use them consistently.

"We have school-aged children, and they do have masks and they're able to follow rules," Nachman said. "Little kids in day care have more trouble following rules."