Pfizer is likely to seek authorization from the Food and Drug Administration for a coronavirus vaccine booster shot for people 18 and older as soon as this week, a government official with knowledge of the situation told ABC News.

The U.S. Centers for Disease Control and Prevention recommended the Pfizer booster shot for certain groups of patients six months after their second dose.

Those eligible patients include seniors, adults with certain medical conditions and adults who work in environments that put them at greater risk for exposure to COVID-19.

-ABC News' Eric Strauss

Despite a looming threat that thousands of Transportation Security Administration workers could be terminated over the federal government’s vaccine mandate, Thanksgiving flights won’t be affected, a person with knowledge of the agency’s plans told ABC News.

Federal workers have until Nov. 22 to get vaccinated or face termination. After the deadline, TSA employees who are not fully vaccinated will get called to have a discussion with supervisors and be counseled and educated on getting vaccinated, the source said.

If workers do not get vaccinated following the first meeting, they will receive a warning, according to the source. Following the warning, workers will be subject to termination, the source said.

Three weeks ago, the TSA said 40% of its workforce was unvaccinated. The agency hasn't provided updated numbers.

-ABC News' Mina Kaji and Amanda Maile

First lady Jill Biden and Surgeon General Dr. Vivek Murthy visited a children's vaccination clinic Monday at Franklin Sherman Elementary School in McLean, Virginia, to promote pediatric vaccinations.

"The vaccine is the best way to protect your children against COVID-19," Biden said. "It’s been thoroughly reviewed and rigorously tested, it’s safe, it’s free, and it’s available for every child in this country, 5 and up."

Franklin Sherman Elementary was the first school to administer the polio vaccine in 1954.

Sixth-grader Everett Munson, who introduced Biden, said, "I'm excited to be vaccinated because now I'll be able to visit my cousins and grandfather. ... I'm looking forward to going places without worrying that I could get COVID and give it to my family, friends or teachers."

Munson also pitched an idea inspired by the school's history.

"Maybe we should even take an idea from the polio vaccine at Franklin Sherman: Everyone should get ice cream after their shots," Munson said.

-ABC News' Michelle Stoddart

The U.S. saw 107,000 pediatric cases last week, an uptick following eight consecutive weeks of declines, according to a weekly report from the American Academy of Pediatrics and the Children’s Hospital Association.

But this is still much lower than the pandemic peak -- 252,000 child cases within one week – which was recorded in early September.

Last week, children accounted for 24% of the cases. Children make up 22.2% of the U.S. population.

Approximately 45.8% of adolescents ages 12 to 17 have been fully vaccinated.

Severe illness due to COVID-19 remains "uncommon" among children, the two organizations wrote in the report. However, AAP and CHA continue to warn that there is an urgent need to collect more data on the long-term consequences of the pandemic on children, "including ways the virus may harm the long-term physical health of infected children, as well as its emotional and mental health effects."

-ABC News' Arielle Mitropoulos