The Blues are the latest New Zealand Super Rugby team to be hit by Covid-19.
The Herald understands one starting player tested positive on Thursday night, and that case numbers at the franchise have since grown.
Beauden Barrett, who had been named to start at first five for the first time since 2020, was a late exclusion when the Blues confirmed their team this evening, replaced by Stephen Perofeta.
The Blues' game against the Highlanders at North Harbour Stadium tonight will go ahead but the remainder of the squad are waiting test results.
In a statement, the Blues confirmed their Covid outbreak that is almost certain to continue to spread throughout the team in the coming days.