A major new study of adults who tested positive for Covid in Ireland has revealed that men were almost twice as likely to be admitted to intensive care with the virus than women.
Elsewhere, the research confirmed what scientists consistently claimed: that age and underlying conditions were the greatest risks for intensive care unit (ICU) admissions and deaths.
Age was the overwhelming factor for deaths, with those who died being an average 75, compared to 59 for hospital admissions. People with underlying conditions were about 10 times more likely to end up in intensive care.
Current and ex-smokers were more than twice as likely to be admitted to ICU. And men faced a 1.8 times higher risk of ICU admission than women.
The data from the Central Statistics Office also showed the average age of those who tested positive was 42, while 53% were male. Analysis covered all 1.4 million adult patients who tested positive between April 2020 and December 2022, and were registered in the Computerised Infectious Disease Reporting system.
The community-wide study, led by University College Dublin (UCD) researchers including Professor Cecily Kelleher and Professor Patricia Fitzpatrick, mirrors global trends and provides the most far-reaching national dataset to date on mortality drivers in the pandemic here.
The authors said: 'This comprehensive study confirmed international findings associated with poor outcomes in Covid. While clinical indications for ICU admission and overall mortality may differ in hospitalised patients, the main drivers of mortality are age, underlying conditions, and disease severity, irrespective of location.'
Professor Kelleher said: 'We found so strongly that age and underlying conditions were very important. Looking at a population this size, it reinforces that highly significant information.
'This was able to tell us that while many people contracted Covid, younger people didn't have the same seriousness on average as older people did.
'The mean age was 42 for incidents of Covid, but for being admitted to hospital it was 59, and for those who died it was 75, so that really shows strongly that age is a very important driver of morbidity and mortality in Covid - it reinforces what we knew.'
The first Covid case in Ireland was reported on February 29, 2020 by the then-chief medical officer Dr Tony Holohan. The severity of cases varied from few or no symptoms to life-threatening pneumonia and death.
Of all the 1,408,249 patients in the study, 31,037 (2.2%) required hospital admission, and 4,432 (0.31%) were admitted to an ICU. A total of 10,855 (0.8%) died.
People with two or more metabolic diseases - such as high blood pressure, diabetes mellitus, and obesity - were six times more likely to die, and 14 times more likely to be admitted to the ICU.
Professor Kelleher said the findings show doctors were correct in their warnings during the pandemic: 'It's very comprehensive that the messaging around age and underlying disease was borne out in what we saw in this analysis, whether it was deaths overall or serious complications of being admitted to an ICU,' she added.
'It's clear where you have a population of older people and those who are vulnerable, they must be protected.'
The UCD academic said the rollout of the vaccination programme was 'the most important' development during the pandemic.
'When you take into account that those older people were either in hospital or long-stay care, that was a risky environment for contracting Covid. That, again, is a very important public health message.
Prof Kelleher also pointed to the importance of supporting people to quit smoking and reducing obesity in the population.
However, she warned that a future epidemic could have very different effects.
'I think the main take-home message for this was that Covid19 was a very significant epidemic strongly associated with age and underlying disease.
'However, for a future epidemic, it might be a completely different virus, a completely different set of circumstances..'
Professor Kelleher added that, today, Covid remains a serious condition to contract - especially for those with risk factors for severe health outcomes.