The number of cases, hospitalizations and deaths are continuing to decline nationwide, according to a new report by the U.S. Department of Health and Human Services.

There has been a four-week downward trend of reported COVID-19 cases – resulting in a 50% decline since the peak on Jan. 8.

However, the rates of adult occupancy in intensive care units remain high in several states, the report found.

So far, 39,037,964 vaccine doses have been administered, with 9% of the population (30.3 million people) having received one or more doses and 3% of the population (8.3 million people) having received two doses.

Since President Joe Biden was sworn in on Jan. 20, 22,512,683 doses have been administered toward his 100 million goal.

ABC News’ Josh Margolin and Arielle Mitropoulos contributed to this report.

Cases of the more contagious U.K. variant of the COVID-19 virus is spreading rapidly through the U.S., as much as doubling every 10 days, a new study suggests.

The study has not peer reviewed, so it has not been scrutinized for inaccuracies or context by specialists.

It is still not known whether the U.K. variant is more virulent or deadly, but it is more transmissible. The Centers for Disease Control and Prevention warned last month that the U.K. variant could become predominant in the U.S. by March if spread the way it did in the U.K.

Vaccines don’t seem to be strongly impacted by the U.K. variant, but scientists are concerned about the efficacy of the vaccines against the South African variant.

-ABC News’ Eric Strauss

A second storm bringing heavy snow to the Northeast has shut down vaccination sites in at least two states.

New York Gov. Andrew Cuomo and New Jersey Gov. Phil Murphy both announced that appointments for Sunday would be rescheduled due to the inclement weather.

Mass vaccination sites located indoors, such as the newly opened Yankee Stadium, will continue as scheduled as they have the infrastructure and equipment in place to ensure people can safely enter and exit the location, according to ABC New York station WABC.

Nine percent of Americans -- 28.9 million people – have received one or more vaccine doses, according to a report from the Department of Health and Human Services.

Two percent of Americans -- 7.5 million people -- have received two doses, the report said.

Deaths are down 4% since the peak on Jan. 13, while hospital admissions have decreased 37% since the Jan. 9 peak, the report said.

ABC News’ Josh Margolin and Brian Hartman contributed to this report.

The European Union's law enforcement agency, Europol, is warning member nations to be on the lookout for fake COVID-19 test certificates.

An increasing number of countries in the EU and beyond are requiring travelers to present proof of a negative COVID-19 test to be allowed entry when coming from a high-risk area. In an early warning notification issued Monday, Europol said several cases have emerged of fraudulent test certificates being sold to travelers, including the arrest of a forgery ring selling negative test results to passengers at France's Paris Charles de Gaulle Airport. The amount charged for the fake documents ranged between 150 to 300 euros ($181-362).

Fraudsters were also caught in the United Kingdom selling bogus test documents for 100 pounds ($137), faking the name of a genuine laboratory on the false certificates, according to Europol.

"The detection of fake COVID-19 negative test certificates confirms that criminals -- be it organised crime groups or individual opportunistic scammers -- seize profitable opportunities once they arise," the agency said in the notification. "As long as travel restrictions remain in place due to the COVID-19 situation, it is highly likely that production and sales of fake test certificates will prevail. Given the widespread technological means available, in the form of high-quality printers and different software, fraudsters are able to produce high-quality counterfeit, forged or fake documents."