The Scottish Labour leader accused First Minister Nicola Sturgeon of failing to “take responsibility” for the crisis surrounding the Queen Elizabeth University Hospital in Glasgow.
Speaking at First Minister’s Questions on Thursday, Mr Sarwar said campaigners were having to do the job of the health board and the government, and pointed out one of the bereaved families had yet to be made aware of the circumstances of their child’s death.
Mr Sarwar has since reported the case to prosecutors.
Police Scotland last month launched a criminal investigation into a number of deaths at the hospital, including that of ten-year-old Milly Main. A review in May found an infection that contributed to her death was probably caused by the hospital environment.
Milly's mother, Kimberley Darroch, told the Scottish hospitals inquiry last month that what happened to her daughter was “murder”.
An independent review published earlier this year criticised health board officials for failures over infection prevention at the hospital. It found 84 children were infected with rare bacteria while undergoing treatment, with a third suffering a severe health impact.
Mr Sarwar told Holyrood that Milly’s case was only referred to the Crown Office after her family applied for a fatal accident inquiry. He said that he met with prosecutors, who asked him to provide the details of another child who had died.
Asked why that death was not subject to an investigation, Ms Sturgeon pointed out the government had established the ongoing public inquiry, which was completely independent of ministers and NHS Greater Glasgow and Clyde.
That inquiry, she said, coupled with the live police investigation, meant it would not be appropriate for her to interfere.
“For all of these reasons, it would not be right, appropriate, or indeed helpful for the families concerned for me to get further into the detail of any of these cases, given the independent processes that are underway,” she told the chamber.
“But I want to leave no-one in any doubt as to how seriously I and the government take these issues, and how determined we are, through the processes we have established in the form of the public inquiry, to get to the answers and the truth.”
But Mr Sarwar said Ms Sturgeon was missing a “fundamental issue”, given those in search of the truth were “having to take on the system to get answers, rather than the system working in their favour”.
He explained: “In one case, Milly’s family is fighting for answers – they now have a criminal investigation into her death. The other family has been kept in the dark and, up until now, there has been no criminal investigation into their child’s death.
“These cases shouldn’t be treated differently. It shouldn’t take a family publicly fighting for answers. That’s not acceptable.
"There should have been criminal investigations launched into both deaths as soon as the circumstances became clear.
“So why is it still falling to whistleblowers, families, and campaigners to do the job of the health board and the job of the Scottish Government for them?”
Reiterating the importance of respecting the independent inquiry and the police investigation, Ms Sturgeon replied: “I hope Anas Sarwar will recognise the worst thing I could do as First Minister in light of the independent processes that are underway would be to in any way inadvertently prejudice any of them by getting further into the detail.
“We’ve done what I think is the right thing to establish the independent inquiry, and it is entirely for the police and the Crown Office to determine what criminal investigations are undertaken.”
Mr Sarwar, however, said it was not acceptable to wait for the outcome of the public inquiry for families to get justice, insisting that it could “take years”.
“Words of sympathy from the First Minister are frankly wearing thin,” he said.
“What is it going to take for Nicola Sturgeon to take responsibility, own this crisis, get a grip of this rotten health board, and get the families the truth and the justice they deserve?”
Ms Sturgeon responded: “A government that has established a full independent statutory public inquiry cannot be said to be a government that is somehow trying to hide away from getting to the truth.
“It is not credible for Anas Sarwar to say a public inquiry was fought for, campaigned for, and then in the next breath say it doesn’t matter, we can’t wait.”
The session also heard Douglas Ross, the Scottish Conservatives leader, ask Ms Sturgeon to “listen to the experts and grieving families” by backing his plans for drug treatment legislation.
A consultation by his party proposes the right of access to rehabilitation and other services for this seeking help with drug and alcohol addiction.
Ms Sturgeon said she couldn’t “engage with a bill which doesn’t yet exist”, but suggested she would be likely to give “fair wind” to the legislation once it is laid in Parliament.
Scottish Liberal Democrat leader Alex Cole-Hamilton raised the issue of the 79,000 Scots believed to be living with long Covid, describing it as potentially the worst mass disabling event since World War Two.
Ms Sturgeon said it was a serious condition, and one we would be “living with for a long time”.
She pointed to the commitments in the government’s long Covid strategy and said health boards could establish specialist provision.