"Today ECDC and EMA will recommend an additional booster to protect the most vulnerable," said the commissioner, Stella Kyriakides, referring to the European Centre for Disease Prevention and Control and the European Medicines Agency.
The agencies are set to issue a joint statement at 0900 GMT on Monday.
"It is crucial that everyone above 60 and all vulnerable persons come forth for a second booster dose as quickly as possible," Kyriakides said in a statement.
EU health agencies have since April recommended a second booster only for those older than 80 and the most vulnerable.
The new recommendation is expected to facilitate national decisions to speed up vaccination campaigns, which have been slowing to nearly a halt in recent months.
"We need to act now to boost the protection of citizens at risk over the summer months," Kyriakides said.
She noted that vaccines currently available for boosters, such as Pfizer's PFE.N and Moderna's MRNA.O, are "highly effective in reducing severe Covid-19."
It is however unclear how effective they are at preventing infections from the newest Covid-19 Omicron sub-variants.
(Reporting by Francesco Guarascio; Editing by Bradley Perrett)

Australian Wiradjuri elder and Indigenous rights activist Aunty Jenny Munro (L) after receiving a dose of Covid-19 vaccine at a pop-up vaccination clinic at the National Centre of Indigenous Excellence (NCIE) in Redfern, Sydney, New South Wales, Australia, 04 September 2021. EPA-EFE/DAN HIMBRECHTS AUSTRALIA AND NEW ZEALAND OUT