Deliveries of the Johnson & Johnson COVID-19 vaccine this month have been "close to the worst-case scenario", officials have said.
Fewer than 80,000 of the Janssen vaccines will have been delivered throughout June.
Initially, close to half a million doses of the one-shot vaccine were scheduled to arrive in Ireland.
However, the Government warned at the end of May that Ireland was set for a "significant under-delivery" of the vaccine.
Stephen Donnelly said the "best-case scenario" was that Ireland would receive just half of the expected one-dose vaccines, but the actual delivery could be much lower than that.
Damien McCallion, National Lead for the COVID-19 Vaccination Programme, today said deliveries have indeed been much lower than initially expected.
He explained: "The original forecast in June was around 470,000.
"Because of the manufacturing problems in the US, that was revised down to a best-case of 235,000, and a worst-case of over 60,000.
"I would anticipate it being closer to that worst-case scenario, based on the recent feedback from Janssen."
The one-shot vaccine is currently being offered by pharmacists, who are administering it to over 50s who have yet to receive any vaccine.
In total, 3.7 million doses of all available types of vaccines have been administered.
Around two-thirds of the adult population have received at least one dose of a vaccine, with around 35% now fully vaccinated.
As of today, vaccine registration is open to everybody aged 36 or older.