CHARLESTON, S.C. (WCBD) – The largest, most ambitious, vaccination effort in U.S. history is underway as hospitals across the nation begin to prepare to receive shipments of Pfizer’s COVID-19 vaccine.

Roper St. Francis anticipates receiving some of those shipments early this week.

President and CEO for Roper St. Francis Dr. Jeff Dilisi says he anticipates the hospitals getting limited shipments of the vaccine.

MUSC is set to start vaccinating their healthcare workers as soon as Tuesday morning.

We do know the state of South Carolina is expected to receive anywhere from 200,000 to 300,000 doses of the Pfizer vaccine.

Mike McDernott of Pfizer says a half million doses were shipped out overnight. Roughly two million more, by the end of the week.

Right now, the U.S. has a contract for 100 million doses that should last through early next year.

“It’s an extraordinary day for science. It’s an extraordinary day for humanity. We’re in discussions with the US government and we look forward to another 100 million doses,” said Mike McDermott, President of Pfizer Global Supply.

145 sites across the United States are expected to receive their shipment by today. Others, getting the vaccine by Wednesday.