The Child and Family Agency, Tusla, has published reports into the deaths of four young people.
The four who died were either in the care of, or were known to, the State's child protection services.
The first report into the death of Danny Talbot, dealt with in the 'Luke' report, said he died accidentally after leaving Health Service Executive care.
It said there was an inadequate response to evidence that the 19-year-old was experiencing child abuse. His needs were not comprehensively assessed at any time.
There was little appreciation that Mr Talbot was at risk of significant harm for considerable periods while in the care of the State, it found.
There were also serious weaknesses in the management and accountability within the HSE, according to the report.
Tusla Director of Policy and Strategy Paul Harrison said the case showed considerable shortcomings in protecting a vulnerable young person.
A second report details the case of Nicholas, who died suddenly at the age of 17 due to respiratory failure arising from a toxic combination of drugs.
He had been referred to the social work department from the age of five.
Child protection services got involved due to neglect, parental conflict, maternal alcohol misuse and family homelessness.
When Nicholas was perceived to be presenting an excessively high risk, a child protection conference was arranged but postponed for five months.
The report said this was an inordinately long time.
It said Nicholas was allowed to remain too long in an environment where drug misuse was the norm.
John, aged four, had a serious illness and died in hospital.
The child's family withheld consent for continuation of the treatment recommended by his hospital consultant, opting instead for alternative and complementary therapy.
The report said the social work department acted promptly.
Neither the HSE nor the hospital staff could have done anything more.
Tusla said this was a difficult case where there was a dispute between John's parents and his medical team.
Susan was 18 months old when she died following a tragic domestic accident.
She lived with her mother and her mother's partner.
Susan was placed in the care of the HSE when an incident occurred, where her mother left her with a minder who became concerned when she could not contact Susan's mother.
Gardaí removed Susan and she was put into foster care.
Susan was initially considered to be at risk of significant harm due to neglect, but was later returned to her family.
The review found no link between the nature and quality of services offered to the family and Susan's death.
In only one case was the child in care at the time of death.
A fifth report has not been published following contact from the family concerned.
The reports were carried out by an independent panel of child protection experts.
They make recommendations on what lessons can be learned from the way the children were treated prior to their deaths.
For the past four years, the National Review Panel has been reviewing the deaths of children in care.
The reports relate to children who died while either in the care of, or known to the State's child protection services. The deaths occurred in different years.
Dr Helen Buckley, chairperson of the National Review Panel, said 91 children and young people known to the child protection services have died since 2010.
This figure includes 12 who were in the care of the State and ten who were in after care.
The aunt of Mr Talbot has said her nephew was failed by the HSE from the "cradle to the grave".
Speaking on RTÉ's News at One, Donna Lamb said she wants to see people held accountable for the HSE failures highlighted in today's findings.
She said lessons must be learnt with new policies and procedures in place to protect children in care.
"We're just asking today why, why we had to ring a social worker 23 times regarding Danny, who was high risk with no response. Why we had to appear in court 21 times and nothing be put in place?”
Ms Lamb said Mr Talbot's family have been trying to highlight what she described as the failures of the HSE in protecting children in care, but that their concerns were not being listened to.
"We've protested outside Dáil Éireann, HSE buildings, we've met with Government. We want people to be answerable to somebody.
"We went from social workers, team leaders, acting child care managers, and still these concerns fell on deaf ears. It is just not acceptable. How many more children have to die before lessons are learnt?"
Later this year, the Child and Family Agency will provide more information about the number of deaths that occurred in 2013 - when the review panel publishes its annual report.
The Children's Rights Alliance said reports of this nature have helped to shine a light into Ireland's recent past and help to eliminate some of the failings and inadequacies in the country's child protection services.