More than 800,000 service members have yet to get their shots, according to Pentagon data. And now that the Pfizer vaccine has received full approval from the Food and Drug Administration, the Defense Department is adding it to the list of required shots troops must get as part of their military service.

The Austin memo does not dictate a specific timeline for completing the vaccinations. But it says the military services will have to report regularly on their progress. A senior defense official said that Austin has made it clear to the services that he expects them to move quickly, and that this will be completed in weeks not months.