Townsville is on standby to hold the NRL grand final on Sunday with new cases of COVID-19 in Brisbane raising fears of an impending lockdown in south-east Queensland.

Suncorp Stadium is scheduled to host its first NRL decider on Sunday evening but those plans are now in danger after at least four locally-acquired cases of coronavirus were detected in the Sunshine State.

Tickets for the premiership decider between South Sydney and Penrith at the 52,000 capacity stadium in Brisbane have already sold out.

At this stage the NRL is not overly concerned about a last-minute switch to Townsville, but the next 48 hours will be critical.

The Queensland government held fire on an immediate lockdown on Tuesday but any additional cases of community transmission could rapidly escalate the situation.

Should a lockdown be announced in the coming days the NRL would then pull the trigger and relocate the season finale to Townsville for the first time.

"Of course I always consider a lockdown and then I work through what we need to do. At this stage, I do not think a lot is warranted," said Queensland's chief health officer Jeannette Young.

"That could change, but I am really, really very comforted by the fact that people do know how to respond and respond very quickly. We have seen that for the last few outbreaks."

Young will not make a decision about the NRL grand final until necessary and understands none of the positive cases attended the two preliminary finals at Suncorp Stadium over the weekend.

Townsville's stadium has a maximum capacity of 25,000.