For example a first dose of AstraZeneca may be followed by a second dose of Pfizer in some instances.
The National Immunisation Advisory Committee has advised vaccines can be mixed in some circumstances.
Health Minister Stephen Donnelly has signed off on the move and confirmed a campaign of booster vaccines is being worked on.
Our Political Correspondent Seán Defoe reports:
"Health Minister Stephen Donnelly received NIAC advice this morning to allow for the mixing of vaccine doses.
It will be limited however. Where someone has had an adverse reaction to dose one, or has serious concerns about taking a second dose of the same vaccine, they may be given another.
For example a first dose of AstraZeneca may be followed by a second dose of Pfizer in some instances.
The HSE and the Department of Health is now working to operationalise the advice.
NIAC is expected to make a recommendation on a potential campaign of booster vaccines next week.
No decision has been taken, but if it was given the go ahead it's likely the first jabs would be given towards the end of September.
The World Health Organisation has asked richer countries not to proceed with boosters until after September, in a bid to help the developing world get vaccinated."
NEW: NIAC has recommended mixing vaccines can be done in limited circumstance. So where someone had an adverse reaction to dose one or has real concerns about taking the second dose a different shot can be used. e.g. an AstraZeneca followed by a Pfizer
— Seán Defoe (@SeanDefoe) August 17, 2021