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."

Ryanair Boss Stands By His Comment Comparing Other Airlines To Rapists
The European Central Bank Announces Interest Rate Increases
Gardaí And Europol Investigate Horse Trafficking In Kildare And Other Counties
Vice Chair Of Kildare Club Believes GAA Are "Seriously Lacking Leadership"
Kildare Highlighted As Having Highest Suicide Rate In Ireland
Four HSE Regions Lose Power Over Day-To-Day Spending
Harris Prepares For First Budget As Finance Minister As FG Think-In Takes Place
Bord Gáis Energy Announce Price Rise