An increasing number of children are being infected with multisystem inflammatory syndrome in children (MIS-C), according to a statement Saturday relased by Los Angeles County Board of Supervisors Chair Hilda L. Solis, supervisor to the First District.

"It is heartbreaking that every day, more than 14,000 Los Angeles County residents are testing positive for COVID-19. It is even more painful to see an increasing number of children being infected by MISC-C. There is a misconception that COVID-19 only impacts those who are older or those with underlying health conditions. At this point in the crisis, we can say for certain that COVID-19 causes severe consequences in people of all ages, including children, and even without underlying health conditions. In Los Angeles County, the Latinx community is bearing the brunt of COVID-19 and MISC-C cases," the statement read.

There have been 51 total cases of MIS-C in children, including one child death. All 51 children with MIS-C were hospitalized and nearly 50% of the children were treated in the intensive care unit. Of the children with MIS-C, 31% were under the age of 5 years old, 38% were between the ages of 5 and 11 years old, and 31% were between the ages of 12 and 20 years old. Latinx children account for nearly 73% of the reported cases, according to the statement.

Experts say the inflammatory syndrome resembles toxic shock syndrome and Kawasaki disease, itself a rare inflammatory disease typically affecting children under the age of 5, and has the potential to be deadly.

-ABC News' Matthew Fuhrman, Olivia Rubin and Soo Rin Kim

Madrid health officials confirmed Saturday that four cases of the new variant of COVID-19 already detected the U.K, have been discovered in Spain, Reuters reported.

The new variant has also been detected in Sweden after a traveler from Britain fell ill on arrival and tested positive for it, the Swedish Health Agency said on Saturday, according to Reuters.

"The employee received the Moderna vaccine Thursday and as is our standard practice was being observed post vaccination by trained nurses. He felt he was developing an allergic reaction and was allowed to self-administer his personal epi-pen. He was taken to the Emergency Department, evaluated, treated, observed and discharged. He is doing well today," Boston Medical Center said in a statement to ABC News.

- Aaron Katersky

Despite health official warnings to stay home this holiday season, and while overall air travel is down nearly 60% from this time last year, the Transportation Security Administration's numbers have jumped, showing more than 7 million people hitting the skies in the past seven days, according to a "Good Morning America" report Saturday.

Over 7.8 million travelers were screened by the TSA since last Friday, Dec. 18 -- the busiest stretch of travel since the beginning of the pandemic.

Dr. Anthony Fauci told The Washington Post that his message for Christmas is to "tone things down," including gathering outdoors when possible, wearing a mask when not eating or drinking, and keeping gatherings to as few people as possible and within your household.

Fauci is not only celebrating Christmas on Thursday, but also his 80th birthday. And for the first time, Fauci won’t be with his daughters for the big day.

"This is the first time since the birth of my daughters, and they are now in their late 20s and early 30s, that we have not been together on Christmas Eve,” Fauci said. “I'm not alone in this feeling that kind of pain of separation from our loved ones.”

His milestone birthday was marked with a surprise Zoom party organized by his wife.

"I want to practice what I preach. I don't want to tell the country to do something that I'm not willing to do myself,” Fauci said. “I was just on a Zoom call with the girls ... I think I lost about a liter of fluid in tears, to be honest, with hearing their expressions of love and concern to me. But we ended it on a happy note because we know that sooner or later, very likely sooner, as we get into 2021 and things get better and vaccines help us, that this time next year we'll be back again with the Fauci family celebrating.”

ABC News’ Stephanie Ebbs contributed to this report.