Johnson and & Johnson is beginning to ship doses of its COVID-19 vaccine following authorization over the weekend, with 3.9 million doses going out this week.
"We think, literally, within the next 24 to 48 hours, Americans should start receiving shots in arms," Johnson & Johnson CEO Alex Gorsky said on NBC's "Today" on Monday. "They're literally rolling out with the trucks as we speak."
The addition of a third authorized vaccine adds to the doses in the US arsenal, but supplies of Johnson & Johnson's vaccine will be limited at first. The 3.9 million doses shipping this week is the entire stockpile, and there will be no additional shipments next week, administration officials said.
The company expects to ramp up somewhat by the end of March, with 20 million total doses by that point, and 100 million by the end of June.
Production delays, though, have limited the initial offering.
Asked about delays, Gorsky said: "Let's remember, this started literally as a genetic code information that was passed on in email 12 months ago."
"Since then, we've been able to do extensive clinical trials involving up to 50,000 patients," he added. "Trial sites around the world. I really can't think of another time in our history where we've been able to ramp up at this kind of pace."
While Johnson & Johnson did not have the headline-grabbing efficacy of the Pfizer and Moderna vaccines, at 66 percent, it was still 100 percent effective in trials at stopping hospitalizations and deaths and was tested during a tougher period when new variants were circulating.