The number of COVID-19 vaccine doses delivered across the United States over the past week dropped 22.5%, but the amount of doses administered increased 13.5%, according to a report from the U.S. Department of Health and Human Services.

The country has also seen a three-week downward trend in new COVID-19 cases, resulting in a 44% decline in the seven-day daily average since the peak on Jan. 8, the report said.

Still, the current number of daily cases remains over twice as high as the numbers during prior peaks.

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

There are currently 91,000 people hospitalized with COVID-19 in the United States -- the lowest since Nov. 28, which was two days after Thanksgiving, according to an ABC News analysis of data compiled by The COVID Tracking Project, a volunteer-run effort to track the U.S. outbreak.

COVID-19 hospitalizations have declined across the country by nearly 30% over the last three weeks.

In the span of three weeks, the national seven-day average of daily COVID-19 cases has declined by 45.6% -- the steepest and most consistent non-holiday-related drop in cases the U.S. has seen since the summer.

ABC News’ Arielle Mitropoulos contributed to this report.

The director of the Africa Centers for Disease Control and Prevention said Thursday that the COVID-19 fatality rate on the 54-nation continent "is becoming very troubling," as it climbs higher than the global average.

John Nkengasong told reporters during a press conference that the death rate from COVID-19 in Africa, the world's second-largest and second-most populous continent, is now 2.6% while the global rate is 2.2%.

Nkengasong said 20 African nations, including South Africa and Sudan, have COVID-19 fatality rates higher than the global average as the continent grapples with new, more contagious variants of the virus. More than 3.5 million people across Africa have been diagnosed with COVID-19 since the start of the pandemic and nearly 89,000 of them have died, according to the latest data from the Africa Centers for Disease Control and Prevention.

The African Union regional bloc has secured 670 million doses of COVID-19 vaccines from various manufacturers. In addition, Africa is expecting around 600 million doses from the vaccine-sharing facility COVAX, which aims to start shipping nearly 90 million doses to the continent in February.

Enough COVID-19 vaccine doses have been secured to inoculate all U.S. Capitol Police personnel, according to Acting Chief Yogananda Pittman, who credited "efforts of the Congressional Leadership, especially House Speaker Nancy Pelosi and the Administration."

The federal police force has been hit hard by COVID-19 infections since the Jan. 6 siege at the U.S. Capitol in Washington, D.C..

"The Department expects delivery of the vaccines to occur shortly, and is already working with the Office of Attending Physician on logistics to administer them to our employees as quickly and safely as possible," Pittman said in a statement Thursday.

ABC News’ Jack Date contributed to this report.

Dr. Stephen Hoge, president of American biotechnolgy company Moderna, said he's hopeful that vaccines can help the U.S. population achieve herd immunity against the novel coronavirus by mid-year.

"It really depends what you think herd immunity needs to be. But if you assume 50 to 70% of the population, then we're working hard ourselves and the other manufacturers to make sure that's a possibility really in the late spring, early summer," Hoge told ABC News chief anchor George Stephanopoulos in an interview Monday on "Good Morning America."

"It's ultimately going to depend upon the delivery of those vaccines, and so that's something that the states and the health care providers in this country are ultimately leading the way on as well as Americans deciding they want to receive that vaccine," he added. But we're optimistic that by the middle of the year, we'll be able to achieve those sorts of numbers."

Moderna is ramping up production of its COVID-19 vaccine and is working to clear any "bottlenecks" in the supply chain, according to Hoge.

"At this point, a lot of the logistical bottlenecks that we're running into are problems we can solve on our own," he noted. "We're in good shape."

Hoge, who was a resident physician in New York City, said data currently shows that existing vaccines are still effective against all emerging strains of the virus. But the variant first identified in South Africa "is of some concern because it looks like it could hide from the vaccine a little better than others," he said.

"So our approach in Moderna is going to be to develop a booster vaccine so that if the South African variant or any other variant becomes a concern, we'll be able to offer a way to identify that, prevent it from hiding from the vaccine," he said.