WASHINGTON — The Food and Drug Administration has informed the drugmaker Moderna that it can put up to 40 percent more coronavirus vaccine into each of its vials, a simple and potentially rapid way to bolster strained supplies, according to people familiar with the company’s operations.
While federal officials want Moderna to submit more data showing the switch would not compromise vaccine quality, the continuing discussions are a hopeful sign that the nation’s vaccine stock could increase faster than expected, simply by allowing the company to load up to 14 doses in each vial instead of 10.
Moderna currently supplies about half of the nation’s vaccine stock. A 14-dose vial load could increase the nation’s vaccine supply by as much as 20 percent at a time when governors are clamoring for more vaccine and more contagious variants of the coronavirus are believed to be spreading quickly.
Two people familiar with Moderna’s manufacturing, who spoke on the condition of anonymity, said retooling the company’s production lines to accommodate the change could conceivably be done in fewer than 10 weeks, or before the end of April. That is because while the amount of liquid in each vial would change, the vials themselves would remain the same size, so the production process would not drastically change. In statement on Friday, Moderna estimated modifications could be made in two to three months.
“It would be a great step forward,” said Dr. Moncef Slaoui, who served as the scientific leader of the Trump administration’s vaccine development program. “I think it will have an impact in the short term.”
Last month, Moderna asked for permission to increase the number of doses in its vials to as much as 15 from the industry standard of 10. The change would cut down on the time required for the final manufacturing phase when millions of tiny bottles are filled, capped and labeled, a longtime bottleneck in injectable drug manufacturing.
The company is also asking regulators to approve changes in how its vaccine is stored and to allow health practitioners more time to use up the doses in a vial once the rubber coating is punctured, all steps to increase the flow into arms.
Dr. Slaoui cautioned that Moderna might still have to gear up its drug production so it had more vaccine to fill the vials. “Whether it will be 40 percent increase immediately or a 20 percent increase at first” is unclear, he said. Another outside expert said the F.D.A. might require an on site inspection of the company’s manufacturing process if it changes.
In a recent email response to questions about the company’s discussions with regulators, Stéphane Bancel, the chief executive officer of Moderna, wrote, “No comment.” Ray Jordan, the company’s spokesman, said talks with federal officials were continuing. More back and forth with the F.D.A. is expected before Moderna gains final authorization for any changes.
On Thursday, President Biden announced that the federal government had locked in a total of 600 million doses of vaccine from Moderna and Pfizer, which developed its drug with a German partner, BioNTech. Because each vaccine requires two doses, spaced three to four weeks apart, that would be enough to cover 300 million Americans.
But getting vaccine shipments out faster remains a top priority. The Centers for Disease Control and Prevention has warned that by next month, a significantly more contagious variant of the virus could become dominant. Another variant that appears to weaken the protection of existing vaccines has also shown up in the United States.
Mr. Biden said on Thursday that the nation would not be able to vaccinate all Americans by the end of the summer, citing “gigantic” logistical challenges. He blamed the Trump administration for not creating a better system to administer shots. But that argument will wear thinner as his time in office continues.
So far, about 10 percent of Americans have received at least one dose of vaccine. Pfizer has delivered about 52 percent of the nation’s supply while Moderna has delivered 48 percent, according to the C.D.C. While both companies are accelerating production, fuller vials from Moderna, if approved, could push it into the lead.
Pfizer’s manufacturing is geared to six-dose vials, but Moderna’s vials have enough free space to accommodate extra doses. Still, there are limits to how much vaccine can be crammed into them.
Too much could lead to cracks in a vial. Each vial must also contain enough room to ensure enough remains to extract the final dose.
The regulations now specify that once punctured, Moderna’s entire vial must be emptied within six hours, so fuller vials could lead to more waste if pharmacists struggle to extract more doses in that time frame.
The industry standard was set at 10 doses partly because the more times a vial’s rubber coating is punctured with a needle, the more risk of contamination. But Dr. Slaoui said those standards were not written for a pandemic that had now claimed the lives of more than 475,000 Americans.
The precise number of doses that can be extracted per vial has become a highly fraught issue. Regulators allowed Pfizer to relabel its vials as containing six doses instead of five, so Pfizer is now getting credit for delivering more doses than before, though the amount has not changed. Six doses can be extracted if health practitioners use specialized syringes, and federal and state officials say that equipment is now included in each shipment of Pfizer vaccine.
Some health practitioners say the same ambiguity exists with Moderna’s product. While the vials are labeled for 10 doses, they have sometimes been able to draw out an 11th dose using specialized syringes.
A third manufacturer, Johnson & Johnson, has asked the F.D.A. to approve its single-dose vaccine for emergency use, and a decision could be made by the end of the month. That company has promised to deliver another 100 million doses by the end of June, but federal officials say the company is still trying to gear up its manufacturing.