President Joe Biden announced Wednesday that the U.S. is donating another 500 million doses of Pfizer's COVID-19 vaccine to low- and middle- income countries around the globe.

"For every one shot we've administered to date in America, we have now committed to do three shots to the rest of the world," Biden said Wednesday.

 
Biden also announced the creation of a new U.S.-EU partnership focused on expanding global vaccination. He noted that the U.S. is working to ramp up manufacturing around the world.

"For example, our quad partnership with India, Japan and Australia is on track to help produce at least 1 billion vaccine doses in India to boost the global supply by the end of 2022. And we're providing financing and helping to strengthen manufacturing in South Africa and produce more than 500 million doses of J&J in Africa, for Africa, next year," Biden said.

Biden announced an initial 500-million-dose commitment in June. The U.S. has so far sent more than 160 million doses to 100 other countries, Biden said.

The latest announcement comes as the World Health Organization has criticized the U.S. for pushing booster doses while much of the world has yet to receive a single shot.

-ABC News' Sarah Kolinovsky

In New York City, officials say they'll be cracking down on mask enforcement on the subway, buses and commuter trains.

Compliance was near-universal earlier in the pandemic when ridership was way down. Now, subway compliance is at about 87%, according to MTA chief safety officer Patrick Warren.

"We want to move up to 100%," Warren said at a Wednesday news conference. 

In recent months the MTA has issued only 41 summonses for noncompliance with mask requirements. 

"We’re going to start handing out summonses more frequently," Warren said. 

-ABC News' Aaron Katersky

With more than 1,500 coronavirus-related deaths reported each day, the U.S. is now averaging the highest number of daily deaths in nearly seven months. 

States with the lowest vaccination numbers are experiencing weekly death rates nearly four times higher than the most vaccinated states, according to an ABC News analysis of federal data.

 
The 10 states with the lowest vaccination rates, where under 45% of residents are fully vaccinated, averaged more than 7.39 deaths per capita each day. The 10 states with the highest vaccination rates, where more than 62% of residents are vaccinated, averaged about 1.89 deaths per capita.

The lowest vaccination rates are in West Virginia, Wyoming, Idaho, Alabama, Mississippi, North Dakota, Georgia, Louisiana, Tennessee and Arkansas.

 
The highest vaccination rates are in Vermont, Connecticut, Maine, Massachusetts, Rhode Island, New Jersey, Maryland, New York, Washington and New Mexico.

-ABC News' Arielle Mitropoulos

Alabama is experiencing a near record-breaking surge in COVID-19 deaths.

“We are seeing a decrease in the number of patients that are in the hospital, but unfortunately, it's not because all of them are getting better and going home to their families... these patients are dying,” Dr. Kierstin Kennedy, chief of hospital medicine at the University of Alabama at Birmingham Hospital, told ABC News Tuesday.

In July, there were only six COVID-19 patients in the UAB hospital, but within four weeks, the number skyrocketed over 100, according to Kennedy.

This latest wave of patients is much younger, primarily consisting of unvaccinated patients, Kennedy said.

“These patients are as sick if not sicker than elderly patients. They're staying in the hospital longer, and they're dying at an alarming rate,” Kennedy said. “It's unlike anything that I've seen.”

Alabama State Health Officer Dr. Scott Harris said Friday, "2020 is going to be the first year that we know of in the history of our state where we actually had more deaths than births -- our state literally shrunk in 2020."

Across Alabama, more than 97% of ICU beds are in use, according to federal data.

Just 41.6% of the state's total population is fully vaccinated.

-ABC News' Arielle Mitropoulos

School districts without a universal masking policy in place at the start of the school year saw a significant increase in COVID-19 outbreaks, according to three new studies released by the Centers for Disease Control and Prevention.

Additionally, school districts in those counties saw more than double the number of pediatric COVID-19 cases during this same period, the studies, released Friday, also found.

The studies further emphasize that school mask requirements, along with other prevention strategies, are critical to reducing the spread of COVID-19 in schools.

Other key findings from the studies include:

- Schools in Arizona that opened without a school mask requirement had a 3.5 higher likelihood of having a COVID-19 outbreak than schools that opened with a school mask requirement.

-During the early part of the 2021-2022 academic school year, almost 2,000 schools have been closed and more than 900,000 students in more than 40 states have been impacted.

- Pediatric cases during the start of the 2021-2022 school year were about half in U.S. counties with school mask requirements than in counties without school mask requirements.

To prevent COVID-19 outbreaks in schools, the CDC recommends a multi-layered strategy including vaccination, universal indoor masking, testing and physical distancing.

-ABC News' Eric Strauss