The length of time the Pfizer/BioNTech vaccine can be kept unopened in a fridge has been increased from five days to one month.
The European Medicines Agency (EMA) previously advised that vials needed to be kept at an ultra-low temperature, between minus 70C and minus 80C, until a few days before use when it can be transferred to a standard medical fridge.
But the EMA said in a statement it had extended the approved storage period for an unopened thawed vial when kept in a fridge between 2C and 8C from five days to one month.
"The change was approved following assessment of additional stability study data submitted to EMA by the marketing authorisation holder," the agency said.
It added increased flexibility in the storage and handling of the vaccine is expected to have a "significant impact" on the planning and logistics of vaccine roll-out in EU member states.
It comes just days after research suggested a 12-week gap between Pfizer doses significantly increases the immune response in older people.
The antibody response in people aged over 80 is three and a half times greater in those who have the second dose after 12 weeks, compared with a three-week interval, the study led by the University of Birmingham, in collaboration with Public Health England, found.
BioNTech said on 10 May there was no evidence its jab needs updating to protect against variants.
The UK government has ordered an extra 60 million doses of the vaccine as part of its plans for a booster programme this autumn.
It is thought that the most vulnerable groups of people, including the elderly, will be offered another jab before next winter.
The extra order brings the total number of Pfizer doses ordered by the UK to 100 million.