MELBOURNE, Australia -- Five members of the Formula One paddock have now been tested for coronavirus after two more Haas employees reported potential symptoms on Thursday morning in Melbourne.

The results of two Haas team members and a McLaren team member, who were tested on Wednesday, are expected later on Thursday and could dictate whether this weekend's season-opening Australian Grand Prix goes ahead.

Speaking before the news broke of the additional Haas team members being tested, Brett Sutton, chief health officer for the sate of Victoria, told Melbourne radio station 3AW that any positive tests among the F1 community could result in the race being called off.

"I think for these three crew members, if they turn up positive, we need to consider what it means for their close contacts and if they have a number of close contacts across a number of crews, then those individuals need to be quarantined," he said. "If that effectively shuts down the race, then so be it, we'll make that call.

Haas team principal Guenther Steiner speaks to media ahead of the Australian Grand Prix weekend. Clive Mason/Getty Images

"It'll depend on those tests. If they are all negative, if everyone else who's got symptoms is negative and hasn't exposed other crew, then I say that they can carry on. But if there are positive crew and they've exposed a number of others, then all of those contacts need to be in quarantine. So it'll be a question of whether the teams have the operational staff to continue."

Haas confirmed that one engineer and three mechanics had been tested, but that it would still be able to operate if they remain in isolation.

Team principal Guenther Steiner said he was still hoping the results would come back negative, but that the team had not been made aware of a contingency plan if not.

"We should get the results in the afternoon," Steiner said. "Until then, I don't know anything, I don't want to speculate and I am not a doctor. Hopefully they come back negative and we keep on going like we want to."

Asked what would happen if the results are positive, Steiner added: "We will cross that bridge if we come to it. We are just waiting to get the result and I hope they are negative.

"Alternative plans are difficult because nobody can come here [to replace them] anymore either time wise or permit wise. So we need to come up with something and in racing you always find solutions. But first I want to know the problem before I find the solution."

The latest communication from F1 said it was taking "a scientific approach to the situation, acting on daily advice from the official health authorities and the advice or measures each host promoter may enact" while motorsport's governing body, the FIA, has set up a Crisis Cell to monitor the situation.

Esteban Ocon of Renault arrives at Albert Park on Thursday wearing a mask. Clive Mason/Getty Images

Williams deputy team principal, Claire Williams, said she believes any decision to cancel the race would likely come from local and federal governments rather than F1 itself.

"I think it's a situation they are managing, they're managing it in close collaboration with the relevant authorities, and at the end of the day it's up to here, I'm not an expert on this, but I believe it is up to the Australian government to make the final call, and that final call is that we are here and we're racing," she said. "As far as I'm concerned there is no case of corona in Formula One but we are playing it literally hour by hour.

"Like F1, like everyone, and every responsible business, we at Williams are monitoring it very closely. We've got a steering committee at Williams that has been in place for a couple of months now to make sure we're acting responsibly and safeguarding everyone that works at Williams and doing what we can do based on the WHO's guidance and that's all we can do at this stage."

Teams have already started taking their own precautions, including cancelling TV media sessions and introducing two-metre exclusion zones around drivers when talking to written media. This weekend's autograph sessions with drivers have also been cancelled, while drivers have been advised not to interact with fans on arrival at the circuit.