The US military should be immediately vaccinated against COVID-19, Defense Secretary Lloyd Austin said, ordering military leaders to set an ambitious timeline for the introduction of vaccinations.

More than 800,000 military personnel have yet to be vaccinated, according to the Pentagon. Now that the Pfizer vaccine has received full FDA approval, the Department of Defense has added it to the list of necessary vaccinations that soldiers must receive as part of their military service.

Austin's memo, obtained by the Associated Press, does not indicate a specific timeline for completing vaccinations.

A senior Defense Department official said Austin made it clear to the services that he expects them to act quickly, and that this will be done in weeks, not months.