RN Courtney Senechal unwraps a special cool box of Moderna Covid-19 vaccines as she prepared to prepare more supplies for use at the East Boston Neighborhood Health Center (EBNHC) in Boston, Massachusetts on December 24, 2020.

Joseph Precious | AFP | Getty Images

The Biden government is working to speed up dosing of Pfizer-BioNTech and Moderna Covid-19 vaccines after U.S. health officials advised states to stop using Johnson & Johnson’s shot while regulators investigate a rare blood clotting problem a senior US official said on Wednesday.

Jeff Zients, the White House’s Covid-19 coordinator, said the Food and Drug Administration’s recommended hiatus on J & J’s vaccine had no “significant impact” on the government’s vaccination program. On Tuesday, the FDA urged states to temporarily stop using J & J’s vaccine “out of caution” after six women developed a rare but serious bleeding disorder that left one dead and another in critical condition.

Some medical experts and former health officials feared the discontinuation of the single vaccine would disrupt the country’s massive vaccination campaign.

According to Zients, the J&J vaccine so far only accounts for 5% of gun shots recorded in the United States. Still, the US government is “doing everything it can to expedite delivery of the Pfizer and Moderna vaccines” while officials work to end the pandemic, he told reporters during a press conference at the White House on Wednesday.

The government currently has contracts with Pfizer and Moderna for 600 million doses, which is enough to vaccinate 300 million Americans, as these two vaccines require two shots three to four weeks apart.

Zients’ comments come a day after Pfizer CEO Albert Bourla said his company ramped up production of its two-shot vaccine and can ship 10% more doses to the US by the end of May than it previously agreed – by to 220 million out of 200 million.

The ramped up production is important as some states like New York have announced plans to use Pfizer’s vaccine in place of the J&J shot for appointments already scheduled.

Zients also said Moderna said it was on track to meet its 300 million can commitment.

– CNBC’s Kevin Breuninger contributed to this report.