The Health Information and Quality Authority (Hiqa) has advised the National Public Health Emergency Team (Nphet) that the duration of immunity following Covid-19 diagnosis should be extended from six to nine months.
Following a review of international evidence and advice from the Covid-19 Expert Advisory Group, Hiqa found most people develop immune memory to the virus that lasts for "at least nine months".
Hiqa deputy CEO Dr Máirín Ryan added: "Across all the studies we examined, the risk of SARS-CoV-2 (Covid-19) reinfection was consistently low, with no increase in infection risk over time."
"Increasing the period of presumptive immunity from six to nine months has widespread positive implications for people.
"For example, a person who has Covid-19 in the last nine months would be exempt from serial testing. A change would also increase the number of under-50s who only need one dose of a Covid-19 vaccine to be considered fully vaccinated," Dr Ryan said.
The extended presumed immunity period could also impact people's eligibility for the EU's digital green certificate for international travel, but Dr Ryan urges that "any policy changes and the evidence behind them are clearly communicated and consistently applied".
A statement from Hiqa adds the impact of Covid variants is "evolving rapidly" and must remain under review.