The U.S. Is Sitting on Tens of Millions of Vaccine Doses the World Needs

“If we have a surplus, we’re going to share it with the rest of the world,” Mr. Biden told reporters on Wednesday, speaking generally about the U.S. vaccine supply. “We’re going to start off making sure Americans are taken care of first.”

Johnson & Johnson, which has authorization for its vaccine in the United States but fell behind on its production targets in both the United States and Europe, recently asked the United States to loan 10 million doses to the European Union, but the Biden administration also denied that request, according to American and European officials.

The European Union has come under fierce criticism for “vaccine nationalism” and protectionism, which intensified last week when Italy blocked a small shipment of doses to Australia, stepping up a tug of war over badly needed shots. Still, the European Union exported 34 million doses of coronavirus vaccines in recent weeks to dozens of countries, even as it faced shortages at home.

As frustrations simmer, some European officials are blaming the United States. The European Council president, Charles Michel, said the United States, along with Britain, “have imposed an outright ban on the export of vaccines or vaccine components produced on their territory.” Asked on Thursday about the American supply of the AstraZeneca vaccine, Jen Psaki, the White House press secretary, told reporters that vaccine manufacturers were free to export their products made in the United States while also fulfilling the terms of their contracts with the government.

But because AstraZeneca’s vaccine was produced with help from the Defense Production Act, Mr. Biden has to approve shipments of doses overseas. Such a move could have huge negative political repercussions as long as Americans are still clamoring for shots.

AstraZeneca is also likely to want liability protection for doses shipped overseas, like it would have in the United States if the vaccine is cleared.

Meantime, regulators in the United States have been waiting for new AstraZeneca data, expected in the next few weeks, from a Phase 3 trial that enrolled 32,000 participants mostly in the United States. AstraZeneca is not likely to report results from an early look at its data, as other vaccine makers have done. It will instead wait for more statistically meaningful results after trial participants have been monitored longer for side effects and more people in the vaccine and placebo groups may have gotten sick, federal officials said. Experts believe the vaccine is unlikely to carry a higher efficacy rate than the shot made by Johnson & Johnson, which uses a similar technology and requires only one dose.