The mandate -- under which the Pentagon says more than 8,000 military personnel have been discharged for refusal to comply -- was scrapped over the objections of US President Joe Biden and Defense Secretary Lloyd Austin, in a victory for Republicans who sought to end it.

While various other US measures aimed at curbing the spread of Covid-19 have previously been relaxed or removed, the Pentagon's vaccine requirement remained on the basis that it protected the health and readiness of military personnel.

But the National Defense Authorization Act (NDAA) for fiscal year 2023, which was previously passed by the House of Representatives, now requires the defense secretary to end the mandate.

The White House supported Austin's opposition to repealing the mandate, but that was not enough to carry the day in Congress.

Republicans, who have insisted that various Covid-19 prevention measures infringe on personal freedom, pushed for the mandate's removal and had threatened to hold up the bill if it did not lift the shot requirement.