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.

Rep. Brad Schneider, D-Ill., said he tested positive for COVID-19 on Tuesday, becoming the third Democrat to do so after sheltering at the Capitol with several Republicans who were unmasked for "several hours” during Wednesday’s siege.

After “narrowly escaping” the violence, Schneider said in a statement, “I was forced to spend several hours in a secure but confined location with dozens of other Members of Congress. Several Republican lawmakers in the room adamantly refused to wear a mask.”

“I am now in strict isolation, worried that I have risked my wife’s health and angry at the selfishness and arrogance of the anti-maskers who put their own contempt and disregard for decency ahead of the health and safety of their colleagues and our staff,” he continued.

Schneider said he hasn't had any symptoms and that he drove home from Washington, D.C., to Illinois.

Rep. Pramila Jayapal and Rep. Bonnie Watson Coleman, both Democrats, have also said they tested positive following the Capitol siege.

Schneider is joining the growing number of Democrats demanding that the House sanction members who don’t wear masks on the House floor.

At a virtual press conference Tuesday, Schneider said, "I don’t know from whom I got this virus or even necessarily if I got it in that room. But I know that my exposure in that room was greater than at any other time through this entire pandemic.”

ABC News’ Ben Siegel and Matthew Vann contributed to this report.