Health authorities in Victoria say they are on a “good trajectory” but residents need to be prepared for the number of cases over coming days.

Chief Health Officer Brett Sutton said while Victorians needed to “ready themselves” for what could emerge over the next 48 hours.

With lockdown measures in place until Tuesday 11.59pm, he said the state was “not opening up with the current numbers”, but no decision had been made about extending lockdown in Victoria.

Professor Sutton said it would take just one essential worker who has to be out and about during lockdown to cause a superspreader event.

“We just need to brace ourselves for any possibility,” he said.

“The response couldn’t have been better … that’s got us on a good trajectory and it is, without question, a better situation than would have been the case without a lockdown.“

Of the 43 positive cases, none are currently in hospital.

COVID-19 testing commander Jeroen Weimar said the fact that all those cases identified today were primary close contacts was reassuring.

“That gives us some confidence that the really fast mobilisation that we’ve seen, the dragnet we’ve put around this at the moment is catching the primary close contacts,” he said.

“But you never know what you’re gonna find in the next 24 hours.

“If we start to see mystery cases popping up at exposure sites that we don’t understand, that we don’t see the connections, that will be a cause for concern.”