The First Minister insisted no data was withheld after The Scotsman revealed officials at Public Health Scotland (PHS) sought to delay a report into care home mortality until after the Holyrood election in May.
The report has never been published.
Care home deaths during the pandemic have been the source of continued controversy.
PHS has emphatically denied there was any external pressure to block publication of the report, and said pre-election civil service rules explained the exploration of the delay.
But speaking at First Minister's Questions on Thursday, Scottish Labour deputy leader Jackie Baillie insisted there was "no barrier" to the report being published as PHS's "own guidance states that they can publish information even in an election period".
She said: "So it seems the report was suppressed for political reasons.
"Now, we know that secrecy and spin are at the very heart of the SNP, but it seems to have infected Public Health Scotland too."
She called for the First Minister to ensure the report is now published.
Ms Sturgeon insisted PHS had been clear no data on deaths was withheld, with the information instead incorporated into a report published on April 21 – prior to the election.
Replying to Ms Bailie, she said: "I really think that is a slur on the good people who work in Public Health Scotland, day in and day out."
She added: "Now, I accept criticism of ministers readily in this chamber. That is a proper part of the democratic process.
"But those working in Public Health Scotland do not deserve that and let me put on the record my thanks to them."
Earlier, former Liberal Democrat leader Willie Rennie said “suspicion about the interference with Public Health Scotland is swirling around”.
He also called for the care homes report to be published.