The HSE is appealing to people to turn up for their second vaccine doses.
Vaccine centres are reporting a 6% "do not attend" rate overall, while GPs are expressing concerns over some people not getting their second AstraZeneca dose, in the hope of being offered a different vaccine.
HSE Chief Clinical Officer, Dr Colm Henry says that this is the wrong approach to take.
"Don't bet on waiting because the best bet you can make is to take that second vaccine, especially in light of this, this expected surge in Delta cases, he said.
"You're better off, fully protected with a full dose schedule from the vaccine, you've been offered and the vaccine that you started with."
There are 47 patients being treated for Covid-19 in hospitals today.
The figure has increased by eight in the space of 48 hours, while a further 13 Covid patients are in intensive care units.
According to the European Centre for Disease Control's (ECDC) threat assessment, those who have received just one dose of vaccine are less well protected from the Delta variant than against other variants.
The ECDC predicts the Delta variant of Covid-19 will represent 90% of all cases in the European Union by the end of August.
The Delta variant - first detected in India - is 40-60% more transmissible than the Alpha (B117) strain and may increase the risk of hospitalisation.
A World Health Organisation spokesperson, Dr Margaret Harris, says countries need to be sensible when lifting restrictions as the Delta variant continues to spread.
"Caution is the watchword for the moment," Dr Harris said.
"The Delta variant is a very effective hitchhiker. It's better than the others at jumping from person to person.
"So, we are seeing that it's got a huge advantage with transmission, and is becoming dominant."