Some experts say they worry that producing more AstraZeneca vaccine in the United States will use up valuable materials that might be better directed overseas or to make other vaccines.
One federal official, speaking on the condition of anonymity to discuss continuing talks, said the government was renegotiating AstraZeneca’s contract, at least partly to shift production to Catalent from Emergent. The official estimated that Catalent could produce about 25 million to 35 million doses of AstraZeneca’s vaccine a month on its new line — a rate similar to that expected from Emergent.
Unlike Johnson & Johnson, Pfizer and Moderna, AstraZeneca has not sought authorization from the Food and Drug Administration to distribute its vaccine for emergency use in the United States. Without an obvious or immediate need in this country, AstraZeneca officials are leaning against pursuing authorization here, according to people familiar with their thinking. The company could still pursue licensure, a lengthier and more complicated process.
The AstraZeneca vaccine appears to be linked to a very rare but sometimes fatal blood clotting disorder, similar to the side effects that led to a pause in administering the Johnson & Johnson’s vaccine in the United States. Many European countries temporarily stopped using the AstraZeneca vaccine this year after a small number of clotting episodes, but they have largely restarted, in some cases with restrictions on what age groups should receive it. The vaccine is being used in 173 countries.
President Biden in late April committed to sharing 60 million doses of AstraZeneca’s vaccine. Jeffrey D. Zients, the White House’s Covid-19 response coordinator, said last month that 10 million of those doses could be released to other countries soon, with the rest to be shared in months, pending an F.D.A. review.
Mr. Biden later expanded his pledge, promising to send 20 million doses of other coronavirus vaccine overseas. Samantha Power, the administrator of the United States Agency for International Development, told lawmakers last week that three-fourths of the excess supply in the United States was likely to go to Covax, an international vaccine-sharing initiative, with the rest distributed through bilateral agreements.
Secretary of State Antony J. Blinken said this week that the administration would announce an overseas distribution plan within two weeks.
Rebecca Robbins and Benjamin Mueller contributed reporting.