The US drug regulator on Tuesday (August 9) authorized Bavarian Nordic’s Jynneos vaccine for emergency use through intradermal injection in individuals aged 18 years and older who are determined to be at high risk of monkeypox infection.

The authorization from the Food and Drug Administration (FDA) will increase the total number of doses available for use by up to five-fold.

According to estimates shared during a briefing by White House monkeypox response coordinator, Bob Fenton, that means up to two million doses available from the 400,000 remaining as of Tuesday.

It also allows individuals younger than 18 years to receive the vaccine by subcutaneous injection if they are determined to be at high risk of monkeypox infection.

The move follows the Biden administration’s decision on Tuesday to allow the FDA Commissioner to grant emergency use authorizations for monkeypox vaccines.

For those aged 18 years and older determined to be at high risk of monkeypox infection, the authorization allows for a fraction of the Jynneos dose to be administered between the layers of the skin.

Two doses of the vaccine given four weeks apart will still be needed, the agency said.

The United States declared monkeypox a public health emergency last week, in an effort to bolster its response to contain the outbreak.