The Food and Drug Administration will evaluate "as quickly as possible" Pfizer's request to expand the emergency use authorization of the drug maker's Covid-19 vaccine to include people ages 12-15 in the United States, FDA Acting Commissioner Janet Woodcock said.
Pfizer on Friday asked the FDA for the amendment.
"While the FDA cannot predict how long our evaluation of the data and information will take, we will review the request as expeditiously as possible using our thorough and science-based approach," Woodcock said on Twitter.
The FDA probably won't ask its Covid-19 vaccine advisory committee to weigh in on the request, the acting chairman of that committee said earlier.
"They're not going to have advisories every time they tweak things," Dr. Arnold Monto said.
The pharmaceutical company said in a statement it will seek similar rulings by other authorities around the world in coming days.
"These requests are based on data from the pivotal Phase 3 trial in adolescents 12 to 15 years of age with or without prior evidence of SARS-CoV-2 infection, which demonstrated 100 percent efficacy and robust antibody response after vaccination with the COVID-19 Vaccine," Pfizer said in a statement.
The FDA currently allows the vaccine's use in people 16 and up.
The other two Covid-19 vaccines -- made by Moderna and Johnson & Johnson -- are authorized for emergency use in people age 18 and older.
Meanwhile, as the country races against Covid-19 variants, more than 1 in 4 adults are now fully vaccinated.
While more than 66 million people have received two doses, more than a third of Americans -- or 112 million -- have received at least one dose, according to data published Thursday by the US Centers for Disease Control and Prevention.
Officials and experts hope to get Americans vaccinated quickly as lockdown fatigue takes its toll and many people are letting down their guard just as more transmissible, and perhaps more deadly, variants of the virus become dominant. In that effort, all 50 states have committed to opening vaccinations to all Americans 16 and up by April 19.
"It's almost a race between getting people vaccinated and this surge that seems to want to increase," Dr. Anthony Fauci said earlier this week, noting Europe is experiencing a spike much like the one experts worry about for the US.
The US added 79,878 new cases Thursday, the highest since March 24. And the country is still averaging above 60,000 new cases a day -- a level Fauci, the director of the National Institute for Allergy and Infectious Disease, said puts the US at risk for another surge. Experts are especially concerned about the spread of the B.1.1.7 variant, first identified in the UK and now the dominant strain in the US.
"I wish we had another three or four months before this B.1.1.7 variant surge started to occur," Dr. Michael Osterholm, director for the Center for Infectious Disease Research and Policy at the University of Minnesota, said this week.
As states including California and Vermont plan to fully reopen this summer, experts are warning that to truly declare victory against the variants, Americans need to get vaccinated and continue measures like social distancing and mask wearing.
Four states reporting adverse reactions to the J&J vaccine
The CDC is aware of several incidents involving adverse reactions to the Johnson & Johnson vaccine in four states, CDC spokesperson Kristen Nordlund told CNN in a statement.
"CDC is aware of several incidents of vaccine recipients experiencing dizziness, lightheadedness, feeling faint, rapid breathing, and sweating (vasovagal or anxiety-related) symptoms following COVID-19 vaccines in Iowa, Colorado, Georgia, and North Carolina," Nordlund said.
Officials in several of those states had previously confirmed to CNN that vaccinations were temporarily paused due to adverse reactions to the J&J vaccine.
CNN has reached out to Johnson & Johnson for comment.
On Thursday, the Colorado Department of Public Health and Environment (CDPHE) said it determined that the adverse reaction suffered by 11 people who received the Johnson & Johnson vaccine at the Dick's Sporting Goods Park vaccination site was "no cause for concern."
"After reviewing each patient's symptoms, analyzing other vaccinations from the same lot of the vaccine and speaking with the CDC to confirm our findings, we are confident in saying that there is no reason for concern," Dr. Eric France, chief medical officer with CDPHE said.
At this time, the CDC and FDA "are not recommending health departments stop administering any lots of COVID-19 vaccine," the CDC spokesperson's statement said. "CDC has performed vaccine lot analyses and has not found any reason for concern."
Severe side effects from the vaccine are uncommon, and many people won't experience any side effects at all. But the CDC said "some people will have pain or swelling at the injection site or fever, chills, or a headache. These typically don't last long and are signs that your body is building protection."
Meanwhile, the National Institutes of Health has begun a clinical trial to determine whether people who are highly allergic or have mast cell disorder are more likely to experience an immediate allergic reaction to the Moderna or Pfizer-BioNTech Covid-19 vaccines, according to the agency's news release.
Mast cell disorder is caused by an abnormal accumulation of a type of white blood cell that leads to allergic reactions.
"The public understandably has been concerned about reports of rare, severe allergic reactions to the Moderna and Pfizer-BioNTech COVID-19 vaccines," Fauci said. "The information gathered during this trial will help doctors advise people who are highly allergic or have a mast cell disorder about the risks and benefits of receiving these two vaccines. However, for most people, the benefits of COVID-19 vaccination far outweigh the risks."
Universities aim to protect against outbreaks
Recent cases of Covid-19 are skewing younger, in part because of activities like school sports and because of more older people being vaccinated, Fauci said Wednesday. Now, some universities are implementing policies to avoid further outbreaks among their students.
The University of Chicago issued a stay-at-home order for students living in residence halls for the next seven days, a letter from the dean and vice president said Thursday.
The order comes after more than 50 cases of Covid-19 were detected among students. It is the largest cluster of cases the school has experienced since the beginning of the academic year, according to the letter.
"Many of these cases may have been connected to one or more parties held by off-campus fraternities over the last week," the letter said.
Meanwhile, the University of Notre Dame in Indiana as well as Syracuse University and Ithaca College in New York are joining the growing list of colleges and universities requiring the Covid-19 vaccine for students prior to returning to campuses in the fall.
Several other schools made similar announcements this week. CNN counts 14 college and universities nationwide that have announced they will require students to be fully vaccinated.
"After a long year, this should give all of us hope for a return to a normal campus experience," said Syracuse Chancellor Kent Syverud. "At every turn, you have demonstrated what it means to be Orange by navigating these extraordinary times with grit, grace and determination. Now, I ask that each of you take the next step by being vaccinated."
Correction: An earlier version of this story misstated how many Americans have received at least one dose of Covid-19 vaccine. It is a third of all Americans.
CNN's Amanda Sealy, Deidre McPhillips, Hannah Sarisohn, Rebekah Riess, Ashley Ahn, Hollie Silverman, Elizabeth Stuart, Lauren Mascarenhas, Elizabeth Cohen and Amanda Watts contributed to this report.