Austin wrote in a memo scrapping the mandate -- under which the Pentagon says more than 8,000 military personnel were discharged for refusing to comply -- that he is "deeply proud" of the Defense Department's efforts to combat Covid-19.

"We have improved the health of our service members and the readiness of the force, and we have provided life-saving assistance to the American people," he wrote.

The memo also said that the department would continue to encourage vaccination, and told commanders that they have "the responsibility and authority to preserve the department's compelling interests in mission accomplishment."

"This responsibility and authority includes the ability to maintain military readiness, unit cohesions, good order and discipline, and the health and safety of a resilient joint force," it adds.

Personnel who were removed from the military solely as a result of the mandate can apply to have the characterizations of their discharges amended, the memo says, but makes no mention of reinstatement -- a move some Republican lawmakers had sought.

The requirement in the National Defense Authorization Act (NDAA) for fiscal year 2023 that the mandate be ended was a victory for Republicans.

Members of the party pushed for the mandate's removal and had threatened to hold up the bill if it did not lift the shot requirement.

Republican Representative Kevin McCarthy, who has since become speaker of the House, argued that the mandate affected recruiting -- an assertion the Pentagon has questioned.

Austin said he has "not seen any hard data that directly links the Covid mandate to an effect on our recruiting."

And Deputy Pentagon Press Secretary Sabrina Singh said the mandate "appears to have very minimal impact on recruiting," and that doing away with it "would impact the readiness of the force."

Singh also said that the majority of respondents to a survey spanning from January to September 2022 said the mandate did not change the likelihood they would consider joining the military.