When will the Pfizer-BioNTech COVID-19 vaccine be ready for kids?

Parents of young children are one step closer to COVID-19 vaccines for their little ones, after Pfizer and BioNTech submitted their request to federal regulators Thursday to authorize emergency use of their coronavirus vaccine for kids ages 5 to 11.

The Food and Drug Administration and the Centers for Disease Control and Prevention will need to sign off on the vaccine before it becomes available to children. An FDA independent expert panel will review the data on Oct. 26, and the CDC committee is expected to follow in days.

That means young kids could be eligible to get their first shot by Halloween.

"With new cases in children in the U.S. continuing to be at a high level, this submission is an important step in our ongoing effort against #COVID19," Pfizer tweeted Thursday. "We’re committed to working with the FDA with the ultimate goal of helping protect children against this serious public health threat."

Pfizer and its German vaccine partner released data from a clinical trial last month indicating their vaccine was safe and effective for children ages 5 to 11 at one-third of the dose given to adolescents and adults. The vaccine could be crucial for elementary schools, where no students have had access to vaccination because of age limits.

Here’s everything to know about the Pfizer-BioNTech COVID-19 vaccine in young children, what to expect and what this could mean for daily life in the U.S.:

Is the vaccine dose for kids as effective as in adults? Is it given in two shots?

Pfizer’s clinical trials in children 5 to 11 did not measure the vaccine’s effectiveness against COVID-19. Effectiveness was “never the intended primary endpoint,” Anderson said.

Instead, they assessed “immunobridging,” which measures the level of immune response in children and compares that to the immune response in adults.

“This was a study of, ‘Do kids that get this dose have an adequate response similar to adults?’” said Jason Gallagher, clinical professor at Temple University’s School of Pharmacy and a clinical pharmacy specialist in infectious diseases at Temple University Hospital.

The study of 2,268 volunteers ages 5 to 11 showed they mounted the same type of strong immune response to the vaccine as teens and young adults. Because Comirnaty, the vaccine's brand name, has already proven effective in older groups, the companies only had to show that the vaccine led to a similar immune response in children – rather than prove it prevented COVID-19 infections. That's why this study was allowed to be conducted with fewer than the 44,000-person trial in adults.

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“This is taking the fact that the vaccine has been shown to prevent disease effectively in adults and, saying this dose did the same immune response in children, and therefore, should be effective," Gallagher said.

All children in the clinical trials were vaccinated, which means there was no placebo group of unvaccinated children to compare to vaccinated children. A clinical trial like this would have delayed authorization well into the next year, Gallagher said.

Health experts say vaccine developers may not get a true sense of the vaccine’s effectiveness until it’s authorized by the FDA and millions of children get their jabs.

The adult dose of the Pfizer-BioNTech vaccine is 30 micrograms, while the companies propose a 10-microgram dose in children ages 5 to 11. As in adults, the vaccine would be given to children in two shots, delivered at least three weeks apart.

What about 11-year-olds?

Doctors advise parents to get their child vaccinated for the dose they're qualified at the moment it's available. They don't recommend children wait until they're 12 years old to receive the 30-microgram dose being given to adults.

"The objective of vaccination is to administer the smallest amount of antigens that elicits an immune response that confers protection while minimizing the side effects," said Dr. Diego Hijano, pediatric disease specialist at St. Jude Children’s Research Hospital.

The only exception is if the child turns 12 within the 3-week period between first and second doses. Then parents might consider waiting a few extra weeks to avoid giving two different doses.

"Each family will have to discuss with their pediatrician and weigh in the risk and benefits of their specific situation and what waiting period, if any, is acceptable to them," he said.

Are there any safety concerns about administering the vaccine to children?

Pfizer says the vaccine at a lower dose is safe for children, but full safety data won’t be available to the public until it’s officially reviewed by the FDA, health experts say.

“Kids often tolerate vaccines better than adults, but it’s hard to speculate beyond what’s in the press release,” said Dr. Sean O’Leary, a pediatric infectious disease specialist at Children’s Hospital Colorado.

The only safety concern experts say may be revealed in the full report is an increased risk of myocarditis – inflammation of the heart – already seen in teenagers and young adults. O’Leary said there’s no reason to believe the mild heart condition will be more common in the 5- to 11-year-old group, as it appears to be a rare side effect even among other age groups.

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Nevertheless, parents shouldn’t be surprised to see some mild cases, Gallagher said, especially after Pfizer and Moderna were asked to increase their trial size in the summer.

“There won’t be zero cases, I’m sure there will be cases,” he said. “I would be scared if my son developed it, but they have been short hospital stays mostly due to caution more than anything else.”

A recent large study published in the New England Journal of Medicine found people are more likely to develop myocarditis from COVID-19 than from the Pfizer-BioNTech vaccine.

Do children experience the same vaccine side effects as adults?

According to the new research, children experienced the same types of mostly minor side effects seen in adolescents and young adults.

The most common side effects seen in adults include pain or swelling at the injection site, headache, chills, muscle aches, fatigue and fever.

Gallagher said one of the reasons researchers decreased the normal vaccine dose from 30 micrograms to 10 micrograms in children 5 to 11 is to reduce the severity of potential side effects.

“A lot of the side effects that people complain about after getting the vaccine is related to the immune response,” he said. “Pfizer went back to the drawing board on dosing and found out that a lower dose (in children) is effective and safe than the dose we’ve been giving to teenagers and adults.”

Could schools require children to be vaccinated?

The Pfizer vaccine is authorized for children ages 12 to 18 and shot mandates to attend school currently vary by state.

The board of the Los Angeles Unified School District – which oversees the second-largest public school system in the country – voted to require students age 12 and up to be fully vaccinated. Those who take part in sports and other extracurricular activities should have taken both shots by the end of October and all other students by Dec. 19. New York City’s school system, the nation’s largest, has only mandated vaccinations for 20,000 student-athletes in certain sports considered at high risk of spreading the virus.

While some districts mull over COVID-19 vaccine mandates, multiple states have banned schools from requiring vaccines.

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Health experts say it’s too soon to speculate if schools will mandate COVID-19 shots after authorization or approval, but vaccines in schools have helped eradicate some diseases in the U.S. like smallpox and polio.

“It’s to prevent disease in children themselves and prevent outbreaks in communities and those school requirements have been long-standing for many decades and they’ve led to very successful control of vaccine-preventable diseases,” O’Leary said.

Will vaccinated children still need to wear masks?

Until a vaccine is approved for children, public health experts, including the FDA's Marks, have said that the best thing parents can do to protect their children – besides getting vaccinated themselves – is to encourage children to wear masks while indoors in public.

Health experts say current CDC guidance recommending fully-vaccinated people to wear masks inside may remain in place even after children 5 to 11 can get their jabs.

“We’ve seen so much COVID-19 circulating in our communities, it will be critical to get the amount of transmission down before it’s likely the CDC might relax those guidelines,” Anderson said.

He reminds parents that children may not have the full intended protection against COVID-19 until two weeks after their second dose and encourages them to continue following CDC and local school guidance regarding masks.

When will Pfizer vaccine be available for younger kids?

The companies are also studying their vaccine in children ages 2 to 5, and 6 months to age 2, but those trials are not yet complete. Younger children are being tested on a 3- microgram dose.

Pfizer has reported it may have data by the end of the year. Before the vaccine becomes available to young children and infants, the company will have to submit the data for FDA and CDC review.

“(Timing) is going to depend on what the data show,” O'Leary said. “I think that people’s best guess is early 2022, but there’s a lot of uncertainty around that guess.”

Contributing: Karen Weintraub, USA TODAY; The Associated Press.

Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT.

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.

This article originally appeared on USA TODAY: When will kids get COVID vaccine? Your Pfizer questions, answered.