Heart disease is the most common underlying health condition in coronavirus patients admitted to hospital intensive care units across the country, it emerged yesterday.
An analysis of the first 327 of the sickest patients with the virus revealed that half (165) had chronic heart disease.
Chronic respiratory disease was diagnosed in 76 patients and another 74 had diabetes.
Another 53 were obese and 34 had asthma.
A further 31 suffered from cancer and 20 had chronic kidney disease.
Underlying illness is known to put people at higher risk of complications and it was the first time chief medical officer Dr Tony Holohan provided an insight into the type of conditions those who are hardest hit by the infection suffered from.
He said in some cases a patient could have suffered from more than one underlying condition.
Dr Holohan warned if today was May 18 the country would not be ready to enter phase one of post-lockdown, but he is "hopeful".
Another 37 deaths from the virus brought the total to 1,375. And 265 newly diagnosed cases of the virus pushed the total to 22,248.
He said there is a persistently high volume of newly infected people emerging from the community, many of them young people.
The number of patients in intensive care has dropped to 86, but a further 196 residents or staff in long-term facilities have tested positive.
They include 160 people in nursing homes, which have also seen another nine clusters develop.
Commenting on the decision to expand testing to the wider population who have at least one potential symptom of the virus, Dr Holohan said he expects it will be able to pick up any area of concern about infection outbreaks in the coming weeks.
He did not think it would overburden the system and there were moves under way to shorten the various stages involved in the chain from the point the patient contacts their GP to them getting a result.
Tracking down contacts of a person who tests positive as fast as possible is vital to stop them infecting others and creating a new chain of transmission, he added.
He said people who are cocooning and have been advised they can now take a walk will continue to be subject to greater restrictions as the country passes through various phases out of lockdown.
"The safest thing is to stay at home and if they take brief exercise they should not visit shops, handle surfaces, contact people, and they should wash their hands when they come home," he advised.
Questioned on whether patients who have not tested positive for the virus are being placed in wards with infected patients, he said there are clear procedures in place to separate both and the policy is that this should not happen.
He said: "This is a very transmissible virus. It is still possible where provision is made to limit the spread of the virus and a separate stream has been created that an infection with Covid-19 can arise in a non-Covid area. The arrangements in relation to acute hospital care are ones they can have confidence in".
People with non-Covid illnesses should continue to present to hospital for treatment, he said.
Meanwhile, the HSE urged anyone with potential signs and symptoms of cancer to contact their GP.
The number of people coming to cancer diagnostic services has decreased since the lockdown began.