The COVAX Facility has announced its plan to distribute more than 330 million doses of COVID-19 vaccines to developing nations in the first half of 2021.

In an interim distribution forecast published Wednesday, the vaccine-sharing facility said distribution would cover an average of 3.3% of total populations of 145 countries taking part in the first rounds. The allocation includes 336 million doses of the Oxford/AstraZeneca vaccine -- 240 million manufactured by the Serum Institute of India plus 96 million made by AstraZeneca -- as well as 1.2 million doses of the Pfizer/BioNTech vaccine.

The COVAX Facility, which is coordinated by the World Health Organization, Gavi, The Vaccine Alliance, and the Coalition for Epidemic Preparedness Innovations, noted that the plan is "non-binding and may be subject to change," with allocations and distributions subject to a number of caveats, including WHO emergency-use approval for vaccines and countries' readiness.

“We will soon be able to start delivering life-saving vaccines globally, an outcome we know is essential if we are to have any chance of being able to beat this pandemic," Seth Berkley, chief executive of Gavi, The Vaccine Alliance, said at a press conference Wednesday.

An additional 3,912 fatalities from COVID-19 were registered in the United States on Wednesday, bringing the country's cumulative total over the 450,000 mark, according to a real-time count kept by Johns Hopkins University.

Wednesday's tally is still less than the country's all-time high of 4,466 new deaths on Jan. 12, Johns Hopkins data shows.

There were also 121,469 new cases of COVID-19 confirmed nationwide on Wednesday, down from a peak of 300,282 newly confirmed infections on Jan. 2, according to Johns Hopkins data.

COVID-19 data may be skewed due to possible lags in reporting over the Martin Luther King Jr. Day holiday weekend last month.

A total of 26,557,031 people in the U.S. have been diagnosed with COVID-19 since the pandemic began, and at least 450,805 have died, according to Johns Hopkins data. The cases include people from all 50 U.S. states, Washington, D.C., and other U.S. territories as well as repatriated citizens.

Much of the country was under lockdown by the end of March as the first wave of pandemic hit. By May 20, all U.S. states had begun lifting stay-at-home orders and other restrictions put in place to curb the spread of the novel coronavirus. The day-to-day increase in the country's cases then hovered around 20,000 for a couple of weeks before shooting back up over the summer.

The numbers lingered around 40,000 to 50,000 from mid-August through early October before surging again to record levels, crossing 100,000 for the first time on Nov. 4, then reaching 200,000 on Nov. 27 before topping 300,000 on Jan. 2.

So far, the U.S. Food and Drug Administration has authorized two COVID-19 vaccines for emergency use -- one developed by U.S. pharmaceutical giant Pfizer and its German partner BioNTech, and another developed by American biotechnology company Moderna and the National Institute of Allergy and Infectious Diseases. More than 33 million vaccine doses have been administered nationwide, according to the latest data from the Centers for Disease Control and Prevention.

The seven-day average for COVID-19 hospitalizations and deaths in the United States has been declining, according to data compiled by The COVID Tracking Project, a volunteer-run effort to track the U.S. outbreak.

The country's seven-day average for COVID-19 hospitalizations was 96,534 on Wednesday, the data shows.

With the exception of Vermont, all U.S. states and territories have seen either declines or no changes in their seven-day COVID-19 hospitalization rates, according to The COVID Tracking Project.

The country's seven-day average for COVID-19 fatalities was 3,039 on Wednesday, the data shows.

"We have seen the 7-day average for new deaths decrease for over a week," The COVID Tracking Project wrote on Twitter. "At the same time, states are reporting an average of 3,000 people dying per day. The data is hopeful and devastating."

All Australian Open events were canceled Thursday after a hotel worker tested positive for COVID-19, organizers said.

All tournament personnel and players are undergoing testing and isolating in their hotel rooms until they get a negative result, according to Tennis Australia, the organizers of the annual tennis tournament.

"We will work with everyone involved to facilitate testing as quickly as possible," Tennis Australia said in a statement Thursday.

Organizers did not say how many of the athletes staying at the Grand Hyatt Melbourne would be affected.

This is the second COVID-19 incident to derail the Australian Open after passengers on a special charter flight bringing professional tennis players to Australia also tested positive for the virus. That incident caused a number of players to be confined to their hotel rooms for two weeks.

ABC News' Zoe Magee contributed to this report.

Zanzibar's First Vice President Seif Sharif Hamad, his wife and a number of his close aides have tested positive for COVID-19, according to a statement from his party.

Hamad, 77, was admitted to a hospital in Tanzania's semi-autonomous archipelago on Friday evening for precautionary measures, after doctors advised him to remain under close medical supervision while he receives treatment, according to the statement.

Hamad's party noted in the statement that the medical conditions of him and his wife are improving.