With a spotlight on COVID-19 vaccine distribution shortcomings, there's another bottleneck that could prevent inoculations from significantly speeding up in the near future: Pfizer's and Moderna's ability to scale up manufacturing and deliver doses to the U.S. government.
The companies promised to deliver 100 million doses apiece to the United States by the end of March. But they'll need to make huge leaps in a short time to meet that goal.
In the last few weeks, they've each been steadily delivering about 4.3 million doses a week, according to an NPR examination of vaccine allocation data. But to hit their targets of 100 million doses on time, they each need to deliver 7.5 million doses a week for the next nine weeks.
"I think it is going to be a real challenge for them to hit that contracted target. There's just no question about that," said consultant John Avellanet, who's advised pharmaceutical companies since the 1990s on manufacturing and compliance issues.
The companies would need everything to go right.
And a lot can go wrong. Equipment breaks and needs repair. Doses need to pass quality tests before they can be shipped. And the production process depends on companies maintaining a steady supply of chemical ingredients, glass vials and skilled labor.
"In some ways, it's almost a miracle that they've been able to produce what they've been able to produce," Avellanet said.