White House pledged to release more vaccine, but stockpile was empty.

WASHINGTON — When Health and Human Services Secretary Alex Azar announced this week that the federal government would begin releasing coronavirus vaccine doses held in reserve for second shots, no such reserve existed, according to state and federal officials briefed on distribution plans.

The Trump administration had already begun shipping out what was available beginning at the end of December, taking second doses directly off the manufacturing line.

Now, health officials across the country who had anticipated their extremely limited vaccine supply as much as doubling beginning next week are confronting the reality that their allocations will not immediately increase, dashing hopes of dramatically expanding eligibility for millions of elderly people and those with high-risk medical conditions.

Health officials in some cities and states were informed in recent days about the reality of the situation, while others are still in the dark.

Concerned New Mexico officials said Friday they were trying to get more information about the state’s allocation.

But the lack of reserve is not expected to interfere with people getting their second shots. States are still getting a regular supply of vaccine, if smaller than they had anticipated, but officials say they are angry and bewildered by the shifting directions.

HHS spokesman Michael Pratt confirmed in an email that the final reserve of second doses had been released to states for order over the weekend but did not address Azar’s comments this week, saying only, “Operation Warp Speed has been monitoring manufacturing closely, and always intended to transition from holding second doses in reserve as manufacturing stabilizes and we gained confidence in the ability for a consistent flow of vaccines.”

Because both of the vaccines authorized for emergency use in the United States are two-dose regimens, the Trump administration’s initial policy was to hold back second doses to protect against the possibility of manufacturing disruptions.

But that approach shifted in recent weeks, according to the officials, who spoke on the condition of anonymity because they were not authorized to discuss the matter.

The result is that next week’s allocations will remain flat.

These officials were told that Operation Warp Speed, the Trump administration’s initiative to speed the development of vaccines and therapeutics, stopped stockpiling second doses of the Pfizer-BioNTech vaccine at the end of last year, instead taking second doses directly off the manufacturing line. The last shots held in reserve of Moderna’s supply, meanwhile, began shipping out over the weekend.

The shift, in both cases, had to do with increased confidence in the supply chain, so that Operation Warp Speed leaders were confident they could reliably anticipate the availability of doses for booster shots — required three weeks later in the case of the Pfizer-BioNTech product and four weeks later under Moderna’s protocol.

But it also meant there was no stockpile of second doses waiting to be shipped, as Trump administration officials suggested this week.

Azar, at a Tuesday briefing, said, “Because we now have a consistent pace of production, we can now ship all of the doses that had been held in physical reserve.”