WASHINGTON: The Pentagon on Wednesday ordered all active-duty service members to be vaccinated with the Pfizer/BioNTech COVID-19 vaccine days after the Food and Drug Administration granted it full approval.

In a memo seen by Reuters, the Pentagon ordered the military to start the process immediately but did not put a specific timeline on when it should be completed.

Earlier in the week it had said that such a move would be coming.

The U.S. military has said that around half the U.S. armed forces are already fully vaccinated, a number that climbs significantly when counting only active-duty troops and excluding National Guard and Reserve members.

Vaccination rates are highest in the Navy, which suffered from a high-profile outbreak last year aboard an aircraft carrier.

Because U.S. service members are generally younger and fitter, relatively few of them have died as a result of COVID-19.

The Pfizer shot became the first COVID-19 vaccine to be fully approved by the FDA. The FDA, which gave the two-dose vaccine emergency-use authorization in December, provided its full approval for use in people age 16 and older based on updated data from the companies’ clinical trial and manufacturing review.