WASHINGTON D.C.: As preparations are underway to begin shipping Johnson and Johnson's COVID-19 vaccines this week, reports have been released indicating that Pfizer and Moderna are increasing production.

News about increased availability of vaccine doses comes as 2.4 million doses of vaccines were administered on Saturday, compared to an earlier average of 1.65 million doses per day.

To date, officials report that 73 million Americans have received at least one dose of the vaccine.

Last week, Congress heard from drug executives who said vaccine production is expected to double or triple in March.

In a statement to the House Energy and Commerce Committee, Pfizer chief business officer John Young said "significant" funding has gone into the company's U.S. manufacturing facilities.

Company officials predict domestic shipments of the vaccine will increase from 4 million to 5 million doses per week, reaching a high of 13 million doses per week.

"We are on track to make 120 million doses available for shipment by the end of March, and an additional 80 million doses by the end of May," Young wrote.

"And, we anticipate all 300 million contracted doses will be made available for shipment by the end of July, enabling the vaccination of up to 150 million Americans."

Young said Pfizer had shipped 40 million doses, as of February 17.

In his comments to Congress, Moderna president Stephen Hoge said his company would double its deliveries by April.

"We have doubled our monthly deliveries since late 2020, and we are aiming to double them again by April to more than 40 million doses per month," Hoge said.

Johnson & Johnson, which only received approval to distribute its vaccine in the U.S. on Saturday, said it now has 4 million doses to ship.

Johnson & Johnson officials also said it expects to ship 20 million of its single-shot doses by the end of March, and 100 million by the end of June.

"We are working with urgency, in collaboration with the government and others, to continue to increase production significantly throughout the year," company vice president Richard Nettles testified.