Moncef Slaoui, Chief Scientific Adviser for Operation Warp Speed (OWS), has said that some Americans could get a coronavirus vaccine by the second week of December.

Slaoui, who is also the former head of GlaxoSmithKline’s vaccines department, is a Belgian-American vaccine researcher.

His comments follow the announcement last week that Pfizer and BioNTech have asked the Food and Drug Administration (FDA) to grant an Emergency Use Authorization (EUA) for their COVID-19 vaccine candidate after it was found to be 95% effective.

Another experimental COVID-19 vaccine, developed by Moderna Therapeutics, is also expected to be submitted for FDA’s EUA soon.

On Sunday, Slaoui told CNN, “Our plan is to be able to ship vaccines to the immunization sites within 24 hours from the approval, so I would expect maybe on day two after approval on the 11th or the 12th of December.”

Millions of Americans could receive the vaccine in the weeks or months after the approval from the FDA, but the OWS adviser said the nation is more likely to achieve herd immunity in 2021.

He said, “Normally, with the level of efficacy we have, 95%, 70% or so of the population being immunized would allow for true herd immunity to take place. That is likely to happen somewhere in the month of May, or something like that, based on our plans.”

Last week, Slaoui told NPR there would be enough vaccines to immunize “about 20 million people by the month of December” and “40 million doses between the two vaccines.”

“But then what’s important to keep in mind is we have four more vaccines in the pipeline — in our portfolio — two of which are in the middle of their phase three trials with already about 10,000 subjects recruited in each one of their trials,” he added.

Slaoui’s comments echoed what Dr. Anthony Fauci, NIAID Director, told NPR’s Morning Edition last week.

Dr. Fauci said that Americans with the “highest priority,” such as frontline health workers and those who are at risk of catching the virus, would likely receive a vaccine towards the end of December. In the United States, the number of coronavirus cases continues to grow at an alarming rate. The virus has affected more than 12 million Americas and killed over 262,000 so far.