Previously the vaccine, developed at the University of Oxford in the UK, was only indicated in Italy for adults aged 55 or under.

But the Italian health ministry published a circular on Tuesday that says the vaccine can be used on everyone between 18 and 65, with the exception of “extremely vulnerable” people.

READ ALSO: Where to register for a Covid-19 vaccine in your region of Italy

The change is due to “new scientific evidence that gives higher estimates of the vaccine's efficacy than those previously reported”, the note said, along with more data about the immune response it produces in people over 55, and guidance from the World Health Organisation that the AstraZeneca vaccine is safe for older adults.

Italy's medicines agency AIFA, as well as the government's panel of scientific advisors, have already signed off on the move. 

AIFA had previously recommended reserving the vaccine for younger adults until more studies had been done on the effects on over-55s. Regulators in Italy and other EU countries have been cautious over the AstraZeneca vaccine on the grounds that the first clinical trials were carried out mainly on younger adults with fewer older participants.

That position had significant consequences for Italy's vaccination schedule, since doses of AstraZeneca began arriving this month but could not be used on over-80s, who are the top priority after health workers. 

READ ALSO: Who is in Italy's Covid-19 vaccine priority groups?

The Health Ministry therefore advised using the Pfizer-BioNTech and Moderna vaccines on people over 80 or with severe medical conditions, while offering AstraZeneca jabs sooner than expected to under-55s working in key sectors like schools or the police service.

Now key workers up to the age of 65 will also be eligible for the shot and, with most regional health services vaccinating in age order, they can expect to get it ahead of their younger colleagues. 

People born before 1956, or those with a serious health condition, will continue to be offered the Pfizer or Moderna vaccines, while others born later – including people with health conditions that make them more vulnerable to Covid-19 but not “extremely vulnerable” – will receive the AstraZeneca version, depending on availability.