Letby has already had an appeal against her other 14 convictions thrown out by the Court of Appeal.
A public inquiry into how she was able to commit her crimes is ongoing at Liverpool Town Hall.
At the Court of Appeal earlier, Benjamin Myers KC, representing Letby, had told the court her original trial in 2023 covered an “exceptional case with exceptional media interest”, which could lead to “exceptional unfairness”.
“We are dealing with the impact of media coverage and public comment arising from the first trial, upon the second,” he added.