About half of all Covid-19 patients in hospital and in intensive care are fully vaccinated against the disease, new figures show.
One-sixth of deaths of people with the virus since April have been categorised as breakthrough infections of fully vaccinated patients, according to Health Service Executive data.
More than one-quarter of ICU admissions since July were also breakthrough infections of fully vaccinated people.
The proportion of vaccinated people requiring treatment in hospital has been increasing over recent months, as the number of vaccinated people in the wider population has risen.
Vaccination has drastically reduced the overall number of infections and reduced the severity of infections where they occur. However, the number of breakthrough infections has increased as the population of vaccinated people has grown.
At the end of August, 54 per cent of Covid-19 patients – or 168 patients – were fully vaccinated. Some 44 per cent were not fully vaccinated, and in 2 per cent of cases, the vaccination status was unknown.
Data on vaccination was available for 311 of the 323 patients then in hospital.
Of 55 patients in ICU, 26 were fully vaccinated, two were partly vaccinated, and 26 had received no vaccinations.
Some 72 per cent of all patients in ICU since late June had an underlying condition.
Between April and August, there were 193 Covid-19 deaths. Of the 178 patients whose vaccination status was known, 30 were at least 14 days after receiving the final dose of vaccine.
Health officials point out that although the majority of Covid-19 cases in hospital now involve vaccinated people, the overall number of hospitalisations is smaller due to the impact of vaccination.
"The rise in vaccinated patients in hospital is not a surprise as more and more people have been vaccinated," said HSE chief clinical officer Dr Colm Henry.
“Vaccines were never going to be 100 per cent effective against infection; their big contribution is in preventing serious illness.”
Whereas in January up to 50 people ended up in hospital for every 1,000 Covid-19 cases, now fewer than 20 hospitalisations occur for the same number of cases.
“But for the vaccination programme, hospitals would have been overwhelmed,” Dr Henry said. “The impact is also clear in terms of reduced translation of numbers of cases into patients who require intensive care.”
About 90 per cent of the adult population has received a full course of vaccination, either two doses or one. People are considered fully vaccinated one week after their second dose of Pfizer vaccine, or two weeks after receiving any of the other three authorised vaccines.
For every vaccinated person requiring admission to hospital with a breakthrough infection, vaccines avert 10 to 12 other severe infections and hospital admissions, Prof Philip Nolan of the National Public Health Emergency Team estimated last month.
Although most cases over the summer have been among younger, unvaccinated people, currently 70 per cent of those in hospital are aged over 50.