US health secretary Alex Azar said on Wednesday that the government was discussing access to more vaccines with covid-19 vaccine producers Pfizer and Moderna Inc."We are actively discussing the issue of acquiring more production capacity with Pfizer, Moderna and other companies," Azar told a conference hosted by the Milken Institute

He said the United States has signed 800 million doses of vaccine contracts with six manufacturers and has up to three billion additional doses.

Pfizer and partner biontech se are expected to send the first batch of vaccines after the food and Drug Administration completes its review of emergency authorization. A vaccine from Moderna Inc. is expected soon.

Azar denied reports that the United States refused to lock in more Pfizer vaccines before other buyers. "The report is inaccurate," he said

The U.S. strategy is to sign up with several vaccine manufacturers that develop different types of vaccines. "We spread the risk," says Azar. "Each vaccine has a different characteristic."

Moderna declined to comment on Azar's comments. According to the agreement between the company and the United States, the country has the right to receive 400 million doses of Moderna in addition to the 100 million doses already ordered. Under the terms of the agreement, the U.S. can add additional doses after emergency approval of the vaccine.