A four-year-old boy who fell off his bike died in a hospital emergency department several days later after clinicians failed to quickly recognise he had developed sepsis.

The boy died in Wellington Hospital in September 2022.

In a report released on Monday, the Health and Disability Commissioner (HDC) found there were a number of deficiencies in the care provided to the boy across multiple departments at the hospital, run by Health New Zealand Te Whatu Ora.

Deputy Commissioner Vanessa Caldwell said the delays in recognising and treating sepsis in the boy amounted to a breach of the Code of Health and Disability Services Consumers' Rights.

"I acknowledge that [the boy's] presentation was challenging and his condition deteriorated rapidly," Caldwell said.

"I also acknowledge that it is not possible to know whether earlier intervention could have altered the tragic outcome.

"But I consider there were missed opportunities to identify this deterioration sooner and initiate the paediatric sepsis [treatment] pathway."

The boy's name and identifying details have been redacted from the published report.

Caldwell's report said the boy first went to a local medical centre with a fever, flu-like symptoms and a sore neck two days after falling from his bike at kindy.

He was diagnosed with a viral illness and sent home with painkillers, but his parents were told to take him back to a doctor if they had any concerns.

Four days later, the boy was taken to the Wellington Hospital ED, and by this time he had also tested positive for Covid-19.

He was taken through for treatment quickly, with a nurse recording that he was lethargic, very sore and in distress, "unable to settle for long, groaning in pain", but not feverish.

An expert's review found the boy was seen by an ED registrar within 60 minutes and a diagnosis was made that included a Covid-related inflammatory syndrome, an autoimmune disease or kidney disease.

"Sepsis was not considered at this point. In my opinion, it should have been," independent adviser Dr Philip Moore said.

The boy had a five-day history of fever and a one-day history of joint swelling and limb pain. He had tested positive for Covid, his pain was severe and he could not weight-bear.

"He was clearly a child with a suspected infection," Moore said.

The boy also had a low temperature on admission, a well-recognised indicator of sepsis.

Over the following hours, he was seen by successive clinicians and the review found there were "missed opportunities" to move faster to gain intravenous access, get blood tests and to give antibiotics.

A paediatric registrar reviewed the boy's case urgently at the request of senior nursing staff at 5.30pm, about six and a-half hours after he presented to ED.

The registrar took immediate steps to escalate the boy's care to senior doctors and started management for presumed sepsis.

The boy received his first antibiotic at 6.07pm.

Despite escalating care, his condition continued to deteriorate and he died at 7.24pm.

Caldwell found aspects of the care provided to the boy by "multiple clinicians" fell below the accepted standard.

"I consider that this reflects system-level issues at Health NZ rather than any individual failings," she said.

"Although I acknowledge that [the boy's] presentation was clearly very complex and his condition sadly deteriorated very quickly, it was the responsibility of Health NZ to ensure that staff had the guidance required to provide services ... with reasonable care and skill."

Health NZ said sepsis was not initially considered as a diagnosis, so the boy was not initiated on the sepsis treatment pathway, and antibiotics were not commenced early in his admission.

Health NZ said it was "deeply sorry" it did not diagnose the boy's condition sooner and acknowledged "how extremely devastating this has been and continues to be" for his family.

Caldwell said Health NZ had made "substantial changes" to its systems since the boy's death.

She recommended it also audit recent paediatric cases to see if the paediatric sepsis pathway has been used, and provide a written apology to the boy's family.