The Hague: The EU's drug regulator on Friday authorised a new technique for monkeypox injections that will allow up to five times more people to be inoculated as supplies of the vaccine run short.

The jab can now be given just below the top layer of skin, or intradermally, instead of fully below the skin, or subcutaneously, as it currently is, the European Medicines Agency (EMA) said in a statement.

The new method uses just one fifth of the amount of Imvanex vaccine but produced similar levels of antibodies, although there was a greater risk of skin irritation, the Amsterdam-based watchdog said.

"National authorities may decide as a temporary measure to use Imvanex as an intradermal injection at a lower dose to protect at-risk individuals during the current monkeypox outbreak, while supply of the vaccine remains limited," the EMA said.

EU Commissioner Stella Kyriakides said the decision was "extremely important as it allows the vaccination of five times as many people with the vaccine supply we have".

"This ensures greater access to vaccination for citizens at risk and healthcare workers," she said in a statement.

While monkeypox had long been endemic in parts of West and Central Africa, since May there have been outbreaks across the world including in Europe and the United States.

- 'Similar levels of antibodies' -

Manufactured by the Danish drug-maker Bavarian Nordic, the Imvanex vaccine was originally approved for use against smallpox, which was eradicated worldwide in 1980.

But studies showed it is also highly effective against the less virulent monkeypox, sparking a worldwide scramble for what is now the only authorised jab against the disease.

The EMA formally approved the extension of its use on July 22 saying it should be administered using deeper, subcutaneous injections.

But on Friday the watchdog said its emergency task force had now found that "when given intradermally, a smaller dose of the vaccine can be used. Given the currently limited supply of the vaccine, this means that more people can be vaccinated".

The task force studied data from a clinical trial involving around 500 adults comparing both kinds of injection.

"People receiving the vaccine intradermally received one fifth (0.1 ml) of the subcutaneous dose (0.5 ml) but produced similar levels of antibodies to those who received the higher subcutaneous dose," the EMA said.

It warned however that there was a "higher risk of local reactions" such as longer-lasting redness and thickening or discoloration of the skin after the shallower injections.

Bavarian Nordic has said it is looking at partnerships with other firms and organisations to "further increase the manufacturing capacity in order to improve global access to the vaccine".