Moderna wants US regulators to allow it to add more of its coronavirus vaccine to each of its vials to speed up the number of vaccinations it can administer to Americans.

The biotech company, one of two federally authorized makers of coronavirus vaccines, said Monday it wants the Food and Drug Administration (FDA) to allow it to add up to 50 percent — five additional doses — of its vaccine in each vial. CNBC reported that Moderna had made the request to the FDA on Feb 5.

If evidence shows it's effective, and the request is approved, it could significantly increase the number of doses available to the public in a few weeks.

"The company is proposing filling vials with additional doses of vaccine, up to 15 doses versus the current 10 doses," Moderna President Stephen Hoge told Reuters. "Moderna would need to have further discussions with the Food and Drug Administration (FDA) to assure the agency's comfort with this approach before implementing."

Moderna was the second drugmaker to receive the FDA's emergency-use authorization approval for its coronavirus vaccine in the US after Pfizer BioNTech. Both Pfizer's and Moderna's vaccines require two doses.

The company said it quickly realized that filling small vials with tiny doses of vaccine was slowing it down. But tests showed that too many doses in one vial could break it. The maximum limit for Moderna's vaccine is 15 per vial.

The drugmaker aims to deliver 100 million doses to the US government by the end of March and 100 million more by the end of June.

Moderna said on Jan 27 that it had held talks with the US government on the possibility of delivering another 100 million doses, which would bring the total to 300 million.

President Joe Biden has made the speeding up of coronavirus vaccinations nationwide a key pledge of his administration. In the past week, the pace of vaccine administration has increased.

Around 1.3 million shots were being given per day on average last week, according to CNN.

As of Monday morning, the US Centers for Disease Control and Prevention (CDC) had administered 42.4 million doses of coronavirus vaccines.

Secretary of Defense Lloyd Austin announced last week that 1,110 active duty service members will support five Federal Emergency Management Agency vaccination centers.

Each team will include service members from across the Army, Navy, Air Force and Marines, according to Pentagon officials.

On Monday, the president and Vice-President Kamala Harris took a virtual tour of a Glendale, Arizona, vaccine site at State Farm Stadium and thanked staff for their efforts. It has administered 160,000 doses to date.

Biden told staff: "Our hope is that we're to be able to not only keep the commitment of getting 100 million shots in people's arms in the first 100 days, I think we'll exceed that considerably, but we've now been able to go out and talk with, personally, the vaccine manufacturers ... thank you for what you're doing."

He added: "We want to get ahead of this virus, not behind it. We want shots for 300 million before summer, that's our hope."

The White House recently announced plans to get local pharmacies to assist in coronavirus vaccine distribution efforts. The federal government will send a million doses of the vaccines to 6,500 pharmacies on Feb 11.

It comes as the US has 27,057,411 confirmed coronavirus cases and 464,372 deaths.

Johnson & Johnson will seek FDA approval for its vaccine soon. But its vaccine may contribute only 7 million doses by April.

The rollout of the coronavirus vaccine comes amid concern about the spread to the US of two coronavirus variants from the UK and South Africa.

The contagious UK strain, known as B.1.1.7, has doubled its prevalence in cases in the US every nine days.

In South Africa, the rollout of the Oxford-AstraZeneca vaccine was halted on Monday after a study showed it offered "minimal protection" against mild and moderate cases of the new variant. The new variant accounts for 90 percent of new cases in South Africa.