As winter storms threatened to upend distribution of Covid-19 vaccines, the White Home on Tuesday mentioned that states collectively would start receiving 13.5 million doses every week — a bounce of over two million doses due partially to a shift in the way in which the federal government is allocating doses of Pfizer’s vaccine. And Jen Psaki, the White Home press secretary, mentioned that a new federal pharmacy program will now present two million weekly doses, a doubling of its preliminary provide.

The will increase have been welcome developments for state officers determined to inoculate extra susceptible Individuals earlier than more contagious variants of virus change into dominant.

The Biden administration has been working with Pfizer, the maker of 1 federally approved vaccine, to get the corporate extra manufacturing provides, together with pumps and filtration items, by way of the Defense Production Act. The administration introduced final week that Pfizer and Moderna, the opposite maker of the vaccine approved in america, will be capable to ship a complete of 400 million by the top of Could, effectively forward of schedule.

The newest increase in provide got here partly as a result of Pfizer, as of this week, is getting credit score for six doses as an alternative of 5 doses per vial, a White Home spokesman mentioned. Two-thirds of the increase was as a consequence of elevated output, the spokesman mentioned. Officers now say there’s an ample provide of specialised syringes wanted to extract the additional Pfizer dose. The White Home warned state officers final week that due to that accounting change, the variety of doses that the federal authorities mentioned it had delivered would shoot up, even when the quantity of vaccine in every vial itself didn’t.

Ms. Psaki advised reporters on Tuesday that with the most recent improve, vaccine deliveries had jumped 57 p.c since President Biden was inaugurated. Administration officers have frequently framed these will increase as Mr. Biden’s accomplishment, despite the fact that, not less than to some extent, the provides have been anticipated to develop as Pfizer and Moderna ramped up manufacturing.

The announcement on Tuesday got here as winter storms within the South continued to disrupt vaccine distribution. Clinics have been closed and shipments have been stalled in states the place the tempo of vaccinations already had lagged behind the nationwide common. Vaccine appointments have been rescheduled or canceled from Texas to Kentucky.

A spokeswoman for the Facilities for Illness Management and Prevention mentioned Tuesday that the federal government was projecting “widespread delays” in vaccine shipments and deliveries within the coming days, as climate was affecting a FedEx facility in Memphis and a UPS facility in Louisville, each vaccine delivery hubs.

“C.D.C. and federal companions are working carefully with the jurisdictions, in addition to manufacturing and delivery companions, to evaluate climate situations and assist mitigate potential supply delays and cancellations,” the spokeswoman mentioned.

Ms. Psaki mentioned that officers have been monitoring the storms and in contact with state and native governments. She mentioned there was a “contingency plan to make sure persons are getting the doses they want at an applicable timeline.”

The rise in doses for pharmacies introduced on Tuesday got here after White Home officers had warned that provides to that program can be extraordinarily restricted at first. Greater than 40,000 pharmacies are anticipated to obtain doses as a part of this system.

Mr. Biden and high federal well being officers have provided various estimates of when most Individuals would possibly be capable to obtain a vaccine. The president final week introduced that the federal authorities had secured 200 million extra doses, bringing the full quantity promised to 600 million, or sufficient to cowl 300 million Individuals. However he warned that logistical hurdles would most definitely imply that many Individuals will nonetheless not have been vaccinated by the top of the summer time.

On Tuesday, Dr. Anthony S. Fauci, the nation’s high infectious illness knowledgeable and adviser to Mr. Biden, revised his personal estimate from final week, when he predicted the start of an “open season” by April. “That timeline will in all probability be extended, perhaps into mid-to-late Could and early June,” he mentioned in an interview with CNN.

Campbell Robertson contributed reporting.