U.S. Rep. Pramila Jayapal, D-Wash., announced Monday night that she has tested positive for COVID-19.

Jayapal was inside the U.S. Capitol in Washington, D.C., when a mob of President Donald Trump's supporters stormed the building last week.

"I just received a positive COVID-19 test result after being locked down in a secured room at the Capitol where several Republicans not only cruelly refused to wear a mask but recklessly mocked colleagues and staff who offered them one," Jayapal wrote on Twitter.

Jayapal and her colleagues in the House of Representatives were in the middle of certifying Electoral College votes when pro-Trump protesters who had been demonstrating outside broke into the Capitol building on Jan. 6. Some members of Congress were forced to evacuate while others had to shelter in place as authorities worked to secure the building.

"Only hours after Trump incited a deadly assault on our Capitol, many Republicans still refused to take the bare minimum COVID-19 precaution and simply wear a damn mask in a crowded room during a pandemic—creating a superspreader event ON TOP of a domestic terrorist attack," Jayapal tweeted.

The congresswoman also called for members of Congress to be fined for not wearing face masks on Capitol grounds.

"Any Member who refuses to wear a mask should be fully held accountable for endangering our lives because of their selfish idiocy," she added. "I'm calling for every single Member who refuses to wear a mask in the Capitol to be fined and removed from the floor by the Sergeant at Arms."

Dr. Brian Monahan, the attending physician of Congress, advised representatives and congressional staff on Sunday that those in the secured room could have, “been exposed to another occupant with coronavirus infection," according to a statement from Jayapal's office.

Jayapal said she has been quarantining since last Thursday -- prior to her positive COVID-19 test -- amid fears she was exposed during the potential "superspreader event."

In the United States, 80,990,232 people live in a county where the average intensive care unit (ICU) capacity exceeds 90%, according to new data compiled by the COVID-19 Hospitalization Tracking Project at the University of Minnesota’s Carlson School of Management.

ICU capacity was most strained in the Southwest, West and Southeast, the report found, with all three regions at 80% ICU capacity or higher.

-ABC News' Brian Hartman contributed to this report.

Dr. Soumya Swaminathan, chief scientist at the World Health Organization, urged people to keep practicing public health measures like mask wearing and social distancing while COVID-19 vaccine production scales up enough to reach billions of people worldwide.

"So, we have to be here a little bit patient, the vaccines are going to come, they're going to go to all countries but meanwhile we mustn't forget there are measures that work," Swaminathan said.

People around the world will need to keep practicing fundamental public health measures at least "for the rest of this year at least," according to Swaminathan.

"Even as vaccines start protecting the most vulnerable, we're not going to achieve any levels of population immunity, or herd immunity in 2021," she added.

-ABC News' Christine Theodorou contributed to this report.

President-elect Joe Biden got his second dose of the two-dose Pfizer/BioNTech vaccine on Monday in Newark, Delaware.

After two doses, the Pfizer vaccine is 95% effective.

Weeks after video emerged of mostly maskless partygoers at U.S. President Donald Trump's Mar-a-Lago Club in Palm Beach, county officials are cracking down.

Palm Beach County sent a letter this week, acquired by ABC News, warning the club and saying officials had met with representatives from the club about violations. Masks are mandatory in the county in all businesses or establishments, and anywhere in public social distancing cannot be maintained. The mandate is currently in place through Jan. 20 -- the same day the county's most famous resident will be exiting the White House.

"Thank you for meeting with us last week to discuss the concerning allegations regarding the Mar a Lago New Year's Eve party and lack of facial coverings being worn during evening activities," the county wrote in the letter addressed to Bernd Lembcke, executive vice president and managing director of Mar-a-Lago Club.

"We recount that you provided masks for all party goers who attended the party and that you provided additional masks for those that walked from the reception area to the main dining ballroom," the letter continued. "Although you provided these important steps, it seemed that based on the video evidence, there was a breakdown in enforcement of the mask orders that led to almost the entire room of guests being without masks during the later evening activities."

The letter also includes a confirmation of the violation, which is a first-time warning, that lays out a fine of up to $15,000 for each potential future violation.

Trump has consistently downplayed wearing masks over the course of the entire pandemic. Despite telling people to wear masks on occasion at official briefings, he also mocked others for wearing them, including President-elect Joe Biden. Many supporters have decried mandates and openly flouted rules, including maskless Trump supporters who stormed the Capitol last week.

ABC News' Will Gretsky contributed to this report.