The CDC's Advisory Committee on Immunization Practices voted Wednesday to endorse Pfizer and BioNTech's Covid-19 booster shots for adolescents ages 12 to 15. Click here to read all of CNBC's Covid coverage.

The CDC's Advisory Committee on Immunization Practices meets Wednesday for a four-hour meeting to review Pfizer and BioNTech's Covid-19 booster shots for kids ages 12 to 15.

The Food and Drug Administration expanded the eligibility of the shots to adolescents on Monday. The FDA said no new safety concerns had emerged after evaluating real-world data from Israel on 6,300 kids ages 12 through 15 who received a Pfizer booster dose.

CDC Director Dr. Rochelle Walensky said earlier Wednesday that booster shots were "critical" to guard against Covid, particularly, the omicron variant.

The meeting starts at 1 p.m. ET and is scheduled to wrap up around 5 p.m. with a vote on whether to recommend the shots at the end of the day. Shots could be administered to kids as early as tonight, depending on how fast Walensky signs off on the panel's recommendation.

CDC panel endorses Pfizer and BioNTech's Covid booster shots for 12- to 15-year-olds

The CDC's vaccine advisory panel on Wednesday endorsed 13-1 third shots of Pfizer and BioNTech's Covid for adolescents ages 12 to 15 at least five months from their second shot as omicron cases surged across the U.S.

Dr. Sara Oliver of the CDC's Covid-19 Vaccines Work Group advised the panel to consider the limited data for the age group as well as the threat of the omicron variant with waning immunity, according to a her presentation.

Oliver said that based on older populations, the risk of myocarditis from the booster doses are lower than those observed after the second dose of a primary series.

—Lauren Feiner

ACIP chair says emergency vaccine meetings need to be 'sustainable' in third year of pandemic

As the world begins the third year of the pandemic, ACIP Chair Dr. Grace Lee said the group needs to find a way to make emergency meetings "feasible, sustainable and impactful."

"We need to be able to support a sustained response, because I don't think things are going to change," Lee said. "It's becoming clear to me we are heading into year three and we are not done by any means."

Lee acknowledged that such meetings place an additional burden on members and CDC staff that attend and present at the discussions. In order to be responsive as an agency, Lee said, they must focus on issues that balance risk-benefit for the overall population and topics that are key to trust and transparency.

–Lauren Feiner

Vaccines for kids 12 and older 'cannot come soon enough'

Hospitals across the nation are seeing a dramatic rise in children's Covid hospitalizations with the arrival of the omicron variant in the U.S. a few weeks ago, making boosters shots for kids 12 and older vitally important, Dr. Julie Boom, director of the Texas Children's Hospital Immunization Project, told the committee.

Almost 7 million children have been diagnosed with Covid so far, with 80,000 of them ending up in the hospital and more than 1,000 dying from the virus, she said. Since the vaccine was first approved for kids 12 and older in May, many of them may already be losing some of that immunity, she said.

"We must do everything in our power to minimize any further detrimental effects to the mental health, physical well being and education of our children," she said. With a surge in cases due to omicron, teachers are again having to balance safety with the needs of students who perform better with in-person learning. "For these reasons, a booster recommendation for children 12 years and older cannot come soon enough," she said.

—Dawn Kopecki

Dizziness, fever among the most common side effects of Pfizer vaccine in children and teens

Dizziness, fainting and headaches were the top three non-serious side effects reported in a review of adverse events in 12- to 15-year-olds who received at least one dose of the Pfizer Covid vaccine.

Among more than 10,400 reports of adverse events analyzed for that age group, 92% of side effects reported were not serious, while 8% were serious, according to a presentation from Dr. John Su of the CDC's Covid-19 vaccine task force. Chest pain was the most common serious side effect, with 440 reports made to the CDC and FDA's Vaccine Adverse Event Reporting System.

Among more than 4,200 reports of adverse events for 5- to 11-year-olds who received at least one dose of Pfizer, 98% of the reports were of non-serious side effects. The most frequent non-serious adverse events reported in that age group were actually of an incorrect dose being administered or a preparation issue with the product. Some also reported vomiting, fever and headache.

Of the serious side effects, there were 29 reports of fever in that age group and 21 of vomiting.

—Lauren Feiner

CDC confirmed 277 cases of myocarditis among 5- to 15-year-olds

The CDC has confirmed 277 cases of myocarditis in 5- to 15-year-olds who received Pfizer and BioNTech's Covid shots.

More than 27.3 million doses have been administered to that age group through the end of last year, said Dr. John R. Su, who sits on the agency's vaccine safety team.

"Most reports were non-serious," Su told the committee, noting about 92% weren't serious. While there were 12 confirmed cases of myocarditis in children ages 5 to 11, most of those were in boys and it was substantially less than in older age groups, he said.

The study also looked at booster doses of Pfizer in 16- to 24-year-olds and found 13 preliminary reports of myocarditis as of late December, when nearly 977,000 doses had been administered. Just four of those reports met the case definition for myocarditis and all patients have since recovered.

One patient in the 5- to 15-year-old age group, however, died after receiving Pfizer's vaccine and was found to have had myocarditis upon autopsy, he said, but it's unclear what role the rare heart inflammatory condition played in that person's death.

"That report remains under active investigation," he said.

—Lauren Feiner

FDA's Marks says omicron prompted agency to act fast on boosters for adolescents

As the omicron variant swept across the U.S., the FDA decided to take three actions to help boost immune protection in the U.S., Dr. Peter Marks, director of the agency's group in charge of vaccine safety, told the CDC advisors.

The FDA decided to shorten the waiting period for Pfizer boosters to 5 months, authorize third shots for kids 5 to 11 with compromised immune systems and clear Pfizer boosters for adolescents 12 to 15. 

Marks said the shorter waiting period for Pfizer boosters will help boost people's immune protection faster as omicron rapidly sweeps the U.S. Studies have repeatedly shown that boosters significantly increase protection against symptomatic infection from omicron.

Marks said the decision to allow third doses for younger kids who have compromised immune systems was a straightforward risk-benefit analysis in which the FDA sought to help boost protection in this vulnerable group as omicron spreads. 

The decision to lower eligibility for Pfizer booster doses to those 12 to 15 was based on the fact that there did not appear to be any safety concerns. The risk of myocarditis, a form of heart inflammation that has been associated with the vaccine, peaks in the 16- to 17-year old age group, among males, Marks said. 

Kaiser study found 43 validated cases of myocarditis or pericarditis in teens

Dr. Nicola Klein, director of the Kaiser Permanente Vaccine Study Center, said in a presentation to the committee that 43 validated cases of myocarditis or pericarditis out of roughly 588,000 12- to 17-year-olds who received at least one shot of Pfizer and BioNTech's vaccine.

Kaiser's research analyzed reports of the rare heart inflammation conditions using data through late December.

The median time for symptom onset in 12- to 17-year-olds who experienced the condition after being vaccinated with the Pfizer vaccine was two days.

About two-thirds of the cases identified occurred in 12- to 15-year-olds, and one-third in 16- to 17-year-olds. The vast majority of validated cases — 86% — were found in boys.

Of the 43 validated cases, 28 were admitted to the hospital, but not the intensive care unit, while 11 were admitted to the ICU. All of the ICU patients were male, according to the findings, with five being Hispanic, four white, one Black and one unknown. Two patient's charts noted the ICU admission was preventative while another was admitted for an unrelated reason.

All 43 were eventually discharged home.

—Lauren Feiner

Vaccine advisory panel met 24 days last year

The CDC's advisory panel on vaccines met 24 days last year as the agency worked to fast-track Covid-19 immunizations, agency official Dr. Amanda Cohn told the panel at the beginning of the meeting. The Advisory Committee on Immunization Practices advises CDC Director Dr. Rochelle Walenksy in deciding how to distribute vaccines authorized by the FDA, but she hasn't always followed their advice.

"So these extraordinary times over the last over the new year we've taken a step back and we're thinking about the best way for ACIP to continue to inform and advise the CDC director on critical Covid vaccine issues," Cohn told the panel. The agency will try to schedule upcoming meetings in advance, she said, "so there will be broad awareness about upcoming opportunities for ACIP to review the data and deliberate in a public transparent setting."

—Dawn Kopecki