US Health and Human Services Secretary Alex Azar said Wednesday the nation will have 40 million doses of a COVID-19 vaccine available by the end of next month.

"By the end of December, we expect to have about 40 million doses of these two vaccines available for distribution pending FDA authorization, enough to vaccinate about 20 million of our most vulnerable Americans," Azar told reporters, referring to Food and Drug Administration.

He said production would "continue to ramp up after that” and the US has "reasons for optimism" as it continues to be hardest hit by the virus that originated in China last year.

His remarks came during a news briefing, days after US biotech firm Moderna announced its coronavirus vaccine candidate is 94.5% effective.

Earlier Wednesday, US drugmaker Pfizer and German biotech firm BioNTech announced their coronavirus vaccine candidate "met all of the study’s primary efficacy endpoints," and is ready to seek approval from the US Food and Drug Administration "within days."

Nearly 250,000 people have died and 11.4 million are infected by the disease, according to a running tally by Johns Hopkins University.(Anadolu Agency)