Three-quarters of Irish population have had Covid-19, study finds

Blood sampling shows 100 per cent have antibodies from infection or vaccination, according to HPSC

Evidence of previous infection is highest among 20 to 29 year olds, at 87 per cent. Photograph:  Agency Photos
Evidence of previous infection is highest among 20 to 29 year olds, at 87 per cent. Photograph: Agency Photos

Three out of four people in Ireland have been infected with Covid-19, data from the State’s infectious diseases monitoring body indicate.

More than two years on from the start of the pandemic, the entire population shows evidence of antibodies to Covid-19 through previous infection or vaccination, according to tests on blood samples carried out for the Health Protection Surveillance Centre (Health Protection Surveillance Centre).

The Health Protection Surveillance Centre is monitoring over time the disease’s seroprevalence, the proportion of people with antibodies in their blood showing they have been exposed to the virus. Blood samples are sourced from the blood donor programme and hospital labs, though only donor samples at present are in the compilation of published data.

Latest monitoring shows 74.3 per cent of people have S+N+ seroprevalence for the virus, which is generally indicative of previous infection, and 100 per cent have S+ seroprevalence, indicating prior infection or vaccination.

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The latest set of data in the national serosurveillance programme is based on almost 13,000 samples collected between July 17th and 24th.

The proportion of samples indicating previous infection, which stood at 20.5 per cent last January, has risen consistently during the year as newer, more transmissible variants of Covid-19 have become dominant and public health measures were eased.

Evidence of previous infection is highest among 20 to 29 year olds, at 87 per cent. This figure falls to 81 per cent among those aged 30-49, and 63 per cent for 50-79 year olds.

While the presence of Covid-19 antibodies indicates previous exposure to the virus or a vaccine, the chance of reinfection remains uncertain. Recent variants have proved effective at reinfecting people, even months after a previous infection.

Another limitation of the study is that blood donors tend to be healthier than the general population.

There were 349 people with Covid-19 in hospital on Wednesday morning, down from 355 the previous day.

This includes 26 people with Covid-19 in intensive care, two down on Tuesday.

According to the Department of Health, 43 deaths of people with Covid-19 were notified in the week up to Wednesday, compared to 25 in the previous week.

Galway University Hospitals had the highest number of Covid-19 patients of any hospital on Tuesday, at 44. The only hospital with no virus patients was the children’s unit in Tallaght Hospital.

Paul Cullen

Paul Cullen

Paul Cullen is a former heath editor of The Irish Times.