The Department of Health has said it has been notified of 1,688 new confirmed cases of Covid-19.
As of 8am, there were 314 patients people in hospital with Covid-19, up from 259 on Saturday and above 300 for the first time since March. Of those, 59 are in ICU.
A week ago, there were 248 Covid patients in hospital, including 43 in ICU.
Health Service Executive (HSE) Paul Reid described the figure as a “very real” threat.
Mr Reid also said almost 6.6 million vaccinations have been administered to date. He said 91 per cent of adults have now been partially vaccinated, while 85 per cent are fully jabbed.
About 135,000 children aged 12 to 15 have registered for a vaccine, while 77,000 have received a single dose, Mr Reid confirmed.
Mr Reid’s comments followed a stark warning from the States’ chief medical officer Dr Tony Holohan on Saturday.
Dr Holohan described the upward trend in serious infection as of “significant concern” and urged people who have not yet opted for vaccination to register “as soon as possible”.
“It is critical for everyone to stay safe by following public health advice as part of their daily routine,” he wrote on Twitter.
While acknowledging that more than eight in 10 adults have been fully vaccinated, Professor Philip Nolan warned that only around 75 per cent received their latest dose more than a fortnight ago. He urged people to wait the one to two weeks it takes for vaccines to become effective.
A member of the National Public Health Emergency Team (Nphet), Prof Nolan wrote on Twitter on Saturday that new Covid cases are “predominantly in young unvaccinated or partially vaccinated adults”.
“This very high incidence constitutes a large force of infection so that incidence is now rising in older vaccinated adults and in children,” he went on.
A further 2,125 cases of Covid-19 were reported in the State on Saturday. Prof Nolan predicted that the incidence of the disease should stabilise as the current vaccination programme finishes and vaccines take full effect through August and September, but he warned the “trajectory between now and then is uncertain and requires we minimise the risks of any social contact”.
Taoiseach Micheál Martin acknowledged on Saturday that the rate of increase in disease incidence is a “concern”. Vaccinations are “key” and people should continue to “watch the fundamentals in terms of social distancing, wearing masks indoors and adhering to the basic guidelines”, he said.
Speaking during homecoming celebrations for the Irish Olympic rowers in Cork, Mr Martin said he shared the concerns of the CMO that Ireland has yet to reach the “peak of the Delta wave”.
He confirmed there will be a “series of meetings” to devise a new roadmap for managing the pandemic over the next couple of months as sections of society reopen, including examining live entertainment and indoor sports.
“We are concerned about [THE]Delta variant and the increase in numbers,” he added.