• Pfizer is planning to deliver 200 million doses of its coronavirus vaccine to the U.S. by May, earlier than its initial forecast of July.
• The company, which developed its vaccine with German drugmaker BioNTech, also said it can potentially deliver 2 billion doses globally by the end of this year.

Pfizer plans to deliver 200 million doses of its coronavirus vaccine to the U.S. by May, earlier than its initial forecast of July, according to slides published Tuesday by the drugmaker ahead of its fourth-quarter earnings call.

The company, which developed its vaccine with German drugmaker BioNTech, also said it can potentially deliver 2 billion doses globally by the end of this year now that health-care providers can extract an additional sixth dose of the vaccine from the vials. In December, the Food and Drug Administration said extra doses from vials can be used after doses were being thrown away due to labeling confusion.

Pfizer had delivered 29 million doses of its two-shot vaccine to the U.S. government as of Jan. 31, according to the company. As of Monday, 17 million of those Pfizer doses have been administered, according to the Centers for Disease Control and Prevention.

The company's Covid-19 vaccine was the first approved for emergency use in the U.S.

Pfizer, like other coronavirus vaccine makers, has been struggling to meet the demand for shots that hopefully will help bring an end to the pandemic. It recently enlisted the help of French drugmaker Sanofi to help produce 100 million doses of its vaccine.

The update on its supply timeline comes hours after Pfizer said it expects to sell about $15 billion in coronavirus vaccine doses this year. The company also raised its full-year earnings guidance to between $3.10 and $3.20 from $3 and $ 3.10, citing "additional refinements" of its vaccine revenue forecast.

The company also said Tuesday it is "prepared to respond" if a Covid variant demonstrates evidence that it is resistant to its vaccine. In recent weeks, U.S. health officials, including Dr. Anthony Fauci, have said they are concerned that vaccines currently on the market may not be as effective in guarding against new, more contagious strains of the virus.

In the slides published Tuesday, Pfizer said patients will "likely need to boost regularly to maintain immune response and to counter emerging variant strains."