86% of those who have died from Covid-19 in Ireland had an underlying medical condition.
While just a small proportion of the fatalities occurred in intensive care units - 69 of 1,403 - an analysis of admissions to ICU gives an idea of the spread of underlying conditions among people who do become critically ill with the virus.
There may be some overlap and some patients may have more than one of these conditions.
Of the first 327 ICU admissions, half had chronic heart disease.
A significant number also had a chronic respiratory disease or diabetes.
A body mass index (BMI) of more than 40, asthma and renal conditions also featured in some patients.
- 165 (50% of the total) had chronic heart disease
- 76 (23.2%) had chronic respiratory disease
- 74 (22.6%) had diabetes
- 53 (16.2%) had a BMI over 40
- 34 (10.4%) had asthma requiring medicine
- 31 (9.5%) had cancer
- 20 (6.1%) had chronic renal disease
The vice president of the Intensive Care Society of Ireland said that while he would have expected patients with chronic lung disease to be at high risk due to the nature of the pandemic, it is surprising that heart disease "seems to be the one that's most prevalent in the patients coming into intensive care."
Dr Colman O'Loughlin, who is a critical care specialist at the Mater Hospital in Dublin, said that because this disease is in its infancy, it is too early to say what this means or make strong conclusions on it.
"It is an association, not a causality," he added.
However, Dr O'Loughlin said that the number of underlying conditions or "comorbidities" a patient does have impact on how long they may have to spend in ICU or recovery.
"Patients who have a fewer amount of comorbidities who get sick enough to come to ICU, seem to have a shorter run of intensive care therapy, and those who have more comorbidities and are slightly older tend to have a longer run of intensive care. As to whether or not they have better or worse outcomes, it's too soon to say that because the numbers are still small and the disease is still in it's infancy relative to what we know about influenza," he said.
Dr Angie Brown from the Irish Heart Foundation said the fact that half of all ICU admissions had chronic heart disease might be worrying for people with the condition, they are not surprising.
Dr Brown said these figures reflect what is being seen worldwide and that people with heart disease are much more vulnerable to the effects of Covid-19.
She said those with heart disease may often have other risk factors (older age, smoking, diabetes) and urged extra caution among these people - continue to cocoon, and practice good hand hygiene and social distancing.
Dr Brown, who is also a consultant cardiologist, said that Covid-19 can attack the heart directly.
"What we are seeing is, sometimes, people without any underlying heart disease, are presenting with heart-related symptoms. So this virus can attack the heart directly causing damage to the heart muscle and mimic the signs of a heart attack. It can also increase the risk of having a heart attack. It seems to make the blood thicker, and more likely to clot," she said.
Dr Brown added that for people who already have the condition, "these effects are much worse because the heart is already under stress and then has to work much harder to cope with this infection."
Earlier this week, Chief Medical Officer Dr Tony Holohan said that health authorities are "generally aware of obesity as a significant risk factor, particularly the very obese, in relation to this condition."
This comes as no surprise for those in the research community, such as Professor Donal O'Shea, the Health Service Executive's clinical lead for obesity.
Prof O'Shea has been working on a research project with Maynooth University's Dr Andy Hogan on the impact that obesity has on the immune system.
"We are seeing that very specific parts of the immune system are compromised. They are the parts of the immune system that deal with viral illness. So it isn't surprising that obesity is emerging as a primary co-morbidity for poor outcomes in Covid-19," he said.
Prof O'Shea added that there is evidence coming from China, Italy and the UK that obesity is associated with a "worse course and a worse outcome" in relation to the virus.
He said that just having obesity on its own "is linked with a worse course and a poorer outcome" and there is no doubt that obesity's links to other conditions like diabetes and hypertension create a bigger risk.
Prof O'Shea said that it will be "vital" to study in detail the factors that give you a poorer outcome when you get Covid-19.
"We are going to be dealing with this for a long time to come and managing conditions that make Covid-19 a worse disease is going to be really important," he said.
