U.S. Rep. Bonnie Watson Coleman, D-N.J. announced Monday that she has received a positive result for COVID-19 from a rapid antigen test and is awaiting results from a polymerase chain reaction (PCR) test.

Coleman said she was forced to shelter in place with unmasked colleagues last week when a mob of President Donald Trump's supporters stormed the U.S. Capitol building in Washington, D.C.

"Following the events of Wednesday, including sheltering with several colleagues who refused to wear masks, I decided to take a Covid test," Coleman, 75, wrote on Twitter. "I have tested positive."

The congresswoman, who previously received one dose of the Pfizer/BioNTech vaccine, said she is experiencing mild, cold-like symptoms and is isolating at home.

-ABC News' Mariam Khan contributed to this report.

Japan has identified a new variant of COVID-19, Dr. Tedros Adhanom Ghebreyesus, director-general of the World Health Organization, said during a Monday news conference.

Japanese health officials alerted the WHO of the new variant, which is different than COVID-19 variants first identified in the U.K. and in South Africa, over the weekend. High transmission of the virus in much of the world is giving it more chances to mutate and evolve into new variants.

"Most notably, transmissibility of some variants of the virus appears to be increasing," Tedros said. "This can drive a surge of cases and hospitalizations, which is highly problematic for health workers and hospitals already close to breaking point," he added.

"At present, the variants do not seem to show increased severity of disease," Tedros said.

-ABC News' Christine Theodorou contributed to this report.

COVID-19 killed more law enforcement officers in the line of duty than anything else in 2020, according to a new report.

The National Law Enforcement Officers Memorial Fund report found that 145 of the 264 federal, state, military, tribal and local law enforcement officer deaths last year were related to COVID-19, with that number expected to rise as more deaths from the virus are confirmed. Other officer fatalities in 2020 included car crashes, heart attacks, stroke and firearm deaths.

Last year marked the highest number of line-of-duty law enforcement deaths since 1974.

-ABC News' Brian Hartman contributed to this report.

It's just over a week into 2021 and the United States has already seen its worst week on record for both COVID-19 infections and deaths.

In the first 10 days of the month, the country has recorded some 2.35 million COVID-19 cases and more than 28,000 deaths from the disease. That works out to be around 163 Americans diagnosed with COVID-19 every minute, and approximately one American death from the disease reported every 30 seconds, according to an ABC News analysis of data compiled by The COVID Tracking Project, a volunteer-run effort to track the U.S. outbreak.

The U.S. has not seen a day with fewer than 100,000 new cases in more than two months, with a record-high average of 243,000 newly confirmed infections every day. In the last week alone, that average of daily cases has increased by approximately 16.3%.

Sunday marked the 41st consecutive day with more than 1,000 fatalities from COVID-19 reported nationwide. The country's average of daily deaths jumped by 21.4% in the last seven days.

Meanwhile, more than 129,000 people are currently hospitalized with COVID-19 across the U.S. -- a number that has hovered around 130,000 for the last several days.

At the current rate, January could surpass December's staggering COVID-19 totals to become the nation's hardest hit month of the pandemic.

ABC News' Brian Hartman and Arielle Mitropoulos contributed to this report.

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.