COVID updates: Team USA figure skater Vincent Zhou tests positive at Olympics

After weeks of surging cases, many U.S. states continue to see impressive declines in their national case averages.

The U.S. is reporting an average of about 543,000 new cases per day, down by about 32.2% in the last two weeks, according to federal data. Two weeks ago the nation was reporting more than 800,000 new cases every day.

Only five states are seeing at least a 10% increase in new cases: Idaho, Maine, Minnesota, Montana and Washington.

But case levels still remain much higher than the nation's previous surges. Experts point out that many Americans who are taking at-home tests are not submitting their results, and thus, case totals may be higher than reported.

Alaska now leads the nation in new cases per capita followed by Washington state, Kentucky and Oklahoma, according to federal data.

-ABC News' Arielle Mitropoulos

Moderna has now received full FDA approval for its COVID-19 vaccine, the second vaccine maker to be granted full approval, after Pfizer.

All three vaccines currently available in the U.S. were granted emergency authorization based on large clinical studies and at least two months of safety data.

Moderna said the full approval was "based on a comprehensive submission package including efficacy and safety data approximately six months after second dose."

-ABC News' Sony Salzman

Canadian Prime Minister Justin Trudeau said he tested positive for COVID-19 Monday morning.

"I’m feeling fine -- and I’ll continue to work remotely this week while following public health guidelines," Trudeau tweeted. "Everyone, please get vaccinated and get boosted."

The initial findings of a long-awaited investigative report into lockdown-breaching parties allegedly attended by British Prime Minister Boris Johnson and his staff were published Monday, saying "there were failures of leadership and judgement."

The probe led by senior civil servant Sue Gray looked into claims that Johnson and his staff flouted COVID-19 restrictions they imposed on England in 2020 and 2021 by holding parties at 10 Downing Street, his official residence and office in London. Johnson has been facing growing anger and calls for his resignation over the allegations, which are also being investigated by London's Metropolitan Police Service.

"At least some of the gatherings in question represent a serious failure to observe not just the high standards expected of those working at the heart of Government but also of the standards expected of the entire British population at the time," Gray wrote in the 12-page report, which included two blank pages. "At times it seems there was too little thought given to what was happening across the country in considering the appropriateness of some of these gatherings, the risks they presented to public health and how they might appear to the public.

"There were failures of leadership and judgment by different parts of No. 10 and the Cabinet Office at different times," she added. "Some of the events should not have been allowed to take place. Other events should not have been allowed to develop as they did."

A spokesperson for the Cabinet Office told ABC News in a statement earlier Monday that Gray "has provided an update on her investigation to the Prime Minister."

Johnson is expected to address members of Parliament during Monday afternoon's session.