Moderna is rapidly increasing production of COVID-19 vaccine for the U.S., and Pfizer is lagging behind. NPR looks at the production trends to see what it means for vaccination drives.

The two companies making COVID-19 vaccines each promised to deliver 100 million doses to the federal government by the end of March. So far, they appear to be running behind.

The COVID-19 vaccine rollout faces another bottleneck: Pfizer and Moderna may be unable to fulfill contractual promises to deliver 100 million doses a piece to the federal government by March 31.

A federal manufacturing contract to increase COVID-19 vaccine production has an unusual clause that could move a company's employees and their families to the front of the vaccination line.

Emergent BioSolutions is under contract with Operation Warp Speed to make COVID-19 vaccines, but the terms could allow employees and their families to get vaccinated ahead of schedule.

The federal government reaches an agreement with Pfizer to buy an additional 100 million doses of the COVID-19 vaccine. NPR explores what that means for the country's supply in the coming months.

The drugmakers will add an additional 100 million COVID-19 vaccine doses to the number that they are already supplying the government. They expect to deliver all the doses by July 31.

Despite being founded a decade ago, Moderna has never had a product make it to market. And the company registered its first factory with the Food and Drug Administration just this week.

With Pfizer's COVID-19 vaccine awaiting Food and Drug Administration authorization, there's speculation about when the U.S. will buy another batch of doses and whether it already missed its chance.

A Pfizer board member says the government declined to buy more doses beyond the initial 100 million already agreed upon. Demand from other countries could complicate future purchases.

The $1.95 billion Operation Warp Speed contract excludes government rights to inventions or production know-how developed in the manufacture of the COVID-19 vaccine.

The $1.6 billion Novavax contract is one of several Operation Warp Speed agreements issued through a third party, Advanced Technology International, and that hadn't been released.

Newly released COVID-19 vaccine contracts include weakened protections against potential price gouging. Several key federal contracts still haven't been disclosed by the government.

To boost the supply of Regeneron's antibody therapy for COVID-19, the federal government entered into a $450 million supply contract. Details of the deal show some safeguards are missing.

Drug industry veteran Moncef Slaoui is a key figure in Operation Warp Speed's push to develop COVID-19 coronavirus vaccines. His employment terms raised concerns about potential conflicts of interest.

Most of the federal contracts with companies involved in the crash program to make COVID-19 vaccines haven't been made public. The lack of disclosure raises questions about accountability.

A panel of doctor and scientists raised questions about the expedited regulatory path the Food and Drug Administration is considering for COVID-19 vaccines.

A milestone in the development of COVID-19 vaccines will take place Thursday when the Food and Drug Administration will ask a panel of experts for advice on how to evaluate the vaccines.

The development of a coronavirus vaccine is nearing the finish, but there have been stumbles. NPR discusses the pause in Johnson & Johnson's trial and the testing stages of other vaccines.

Members of Congress and advocacy groups say Operation Warp Speed should release its contracts with vaccine makers after NPR reporting found the terms of many aren't public.