WASHINGTON (Reuters) – The White House will announce on Friday that millions of federal contractors must be vaccinated against COVID-19 by Dec. 8 and that the administration will add clauses to future government contracts mandating inoculations, officials told Reuters.

Although President Joe Biden issued an executive order on September 9 that required federal contractors to require vaccinations, many U.S. contractors waited for formal guidance before proceeding.

According to the White House Office of Management and Budget, this requirement will “reduce worker absence, decrease labor costs and improve efficiency of subcontractors and contractors working for the Federal Government.”

The guidelines to be issued Friday state that contractors must receive all required vaccinations no later than December 8, and that they should be up to date by the day of the performance of any extended or new contracts.

According to a federal official, all procurement contracts are generally covered by the government. This includes service contracts. Officials expect that the requirements also will apply to contracts with the government for specific products like defense contracts.

The White House stated earlier this month that all federal workers must have been fully immunized against COVID-19 by Nov. 22.