Pfizer may face challenges manufacturing Covid-19 vaccine: Top US official

However, officials did not outline what the specific manufacturing challenges were

US officials are working with Pfizer Inc to help maximise production capacity for its Covid-19 vaccine after the drugmaker told them it may be facing production challenges, U.S. Secretary of Health and Human Services Alex Azar said in a Wednesday press call.

Pfizer did not immediately respond to a request for comment, but it's Chief Executive Albert Bourla told CNBC earlier this week the company was asking the U.S. government to use the Defense Production Act to relieve some "critical supply limitations," particularly in some components. He did not provide further details on the areas of shortage.

Officials did not outline what the specific manufacturing challenges were. They said they are very familiar with the manufacturing materials and equipment needed to make vaccines based on their work with other drugmakers.

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"We have recently been informed by them finally of various challenges that they might have in their manufacturing and we will ensure that by whatever mechanism, that we provide them full support to ensure that they can produce for the American people," Azar said.

Ugur Sahin, chief executive of Pfizer's partner, BioNTech SE, told Reuters last week that Pfizer's initial 2020 production target of 100 million doses was halved earlier this year in part over issues with raw materials supply. He said that has since been resolved and manufacturing has begun at scale.

The U.S. government is in active talks with Pfizer to secure 100 million additional doses, U.S. Operation Warp Speed chief adviser Dr. Moncef Slaoui said on the call. It had previously contracted with Pfizer for the option to buy up to 500 million additional doses at an unspecified price.

Officials said on Wednesday the United States has already contracted for 300 million vaccine doses between the Pfizer/BioNTech shot and one from Moderna Inc in the coming months, and 900 million doses in total from drugmakers developing Covid-19 vaccines.

Moderna's vaccine is likely to be authorized as soon as Friday, they said.