• Drugmakers told lawmakers this week that they are ramping up manufacturing Covid-19 vaccines.
• Pfizer Chief Business Officer John Young said early delays in boosting manufacturing caused the company to miss an early target for delivery of doses to the U.S.
• Pfizer and Moderna both said they are now confident about the outlook going forward, adding that they hope to at least double production next month.

Drugmakers are significantly ramping up Covid-19 vaccine production after working out manufacturing issues that initially delayed the first shots, executives told Congress this week.

Rep. Diana DeGette, D-Colo., said Tuesday that "the amount of supply has fallen short of expectations" as lawmakers pressed Pfizer and Moderna executives on why they missed early U.S. delivery targets of their vaccines.

Pfizer CEO Albert Bourla said in October that the company could deliver between 30 million and 40 million doses by the end of the year, but the company only met the lower end of that goal last week, DeGette said at a hearing of the House Committee on Energy and Commerce.

"We did initially experience some problems with the initial ramp up of our vaccine," Pfizer Chief Business Officer John Young testified at the hearing. "In common with other panelists here, we've been in the process of developing a manufacturing process for a vaccine product that we've never made before."

Young said shortages of some raw materials were among the early production constraints, but added that the company is on track to deliver 300 million doses of the two-shot vaccine before the end of July.

Rep. Jerry McNerney, D-Calif., similarly questioned Moderna for failing to hit initial delivery projections. Moderna President Dr. Stephen Hoge defended the company's progress, noting that it just narrowly missed its goal of delivering 20 million doses by the end of last year. Moderna, he said, delivered 17.8 million doses by Dec. 31.

"We ultimately had never, when we were trying to make those estimates, manufactured doses at this scale," Hoge said at the hearing. "We had a lot to learn along the way, and many of the challenges that we ran into were the normal sort of training experiences as you train people to operate a complicated process."

He added that the company is "very pleased" with its current production rate, noting that it delivered 9 million doses last week and is on track to double its current pace of production.

New manufacturers

Manufacturers of other vaccines, which have not yet been authorized by the Food and Drug Administration, also testified about their preparedness to quickly provide doses upon regulatory authorization in the U.S.

Johnson & Johnson's vice president of U.S. medical affairs, Dr. Richard Nettles, said that, if authorized for use in the United States, the company plans to ship more than 20 million doses to the federal government by the end of March. An FDA panel is meeting on Friday to review data on the one-shot vaccine and it could be authorized as soon as this week.

Dr. Ruud Dobber, president of AstraZeneca's biopharma business, testified that the company expects to hear back on regulatory authorization from the FDA in early April regarding its two-shot vaccine. He said the company has manufactured enough doses to "release instantly 30 million doses" and up to 50 million by the end of April. The company will then produce between 15 million and 25 million doses every month until its obligation of 300 million doses is met, Dobber said.

And John Trizzino, chief commercial officer of Novavax, said his company is ready to send 100 million doses of its Covid-19 vaccine by the end of June as soon as it wins emergency approval.

'Variant vaccine'

The executives said they believe the currently available vaccines are still effective against the emerging threat of new mutated variants of the coronavirus, but they've all begun to test or prepare to test booster shots to specifically target them.

The FDA released new guidance on Monday to clarify to vaccine makers what the regulatory process will look like for potential Covid-19 booster shots that are designed to target new variants. The agency said it won't require lengthy clinical trials, but instead will allow companies to apply for amendments to their existing emergency use authorization applications.

"We have been in productive conversations with the FDA," Moderna's Hoge said. "Ultimately, they have the responsibility to set the bar and make recommendations on whether the vaccine is effective and safe against those new variants, but we are hopeful that we will be able to do it without large, randomized phase three trials."

Pfizer's Young echoed Hoge, saying that the process should resemble "more of a seasonal flu-like process," meaning that a smaller number of patients are required to participate in the clinical trials.