"The time will come and we are not far away from that time," Professor Nigel McMillan, director of infectious diseases and immunology at the Menzies Health Institute in Queensland, said. "If the government acts too early and locks everything down too soon there is a concern people will get sick of it because there is only so much time people will follow such extreme measures. We really have to enact it at a time when it will have the most impact at stopping the spread." Loading Replay Replay video Play video Play video Professor McMillan predicted the time for a nationwide lockdown would be within the next week. The doctors are demanding authorities immediately implement strict lockdown and social distancing and warn vital equipment, such as more respirators, is yet to arrive in some hospitals.

They are also calling for ramped up health resources, including personal protective equipment for frontline workers and re-purposed hospitals able to cope with the onslaught of critically ill patients. Dr Kelly, who is based in NSW, specialises in care for patients requiring the most extreme form of heart and lung support and has worked in some of the nation's top hospitals. He is among the thousands of doctors who will be on the frontline of the pandemic if it overwhelms the nation’s intensive care units. He said doctors were extremely worried rates of infections being seen around Australia would continue to jump, "as they have done in every country in the world until we move to stricter measures".

"Doctors are not activists; they don’t put their names or emails or roles to petitions," he said. "To have thousands of my colleagues sign it indicates just how united we all are on this and how worried we are about it." Dr Kelly and his colleagues had intended to release the second petition on Sunday, but delayed it because of announcements by the Victorian and NSW premiers moving towards a total lockdown of those states. But while many companies were forced by government edict to close, many non-essential businesses remain open. "We accept that these are really tough decisions for governments, but the international experience is that there simply is no other option than a total shutdown of all non-essential services and strict social distancing," Dr Kelly said.

Loading Dr Chris Moy, chair of the Australian Medical Association's ethics and medico-legal committee, said Australia had among the highest rates of COVID-19 testing in the world and was in a far better position than Italy, Britain or the US. "I respect them [the doctors] as experts in their fields in specific health areas and of course their input is absolutely their right," he said. "But we also need to respect the decisions of the doctors who are public health specialists and epidemic modellers – of which Australia has among the best in the world." Dr Moy said Chief Medical Officer Brendan Murphy and his deputy Paul Kelly were "fully aware of the weight of responsibility on their shoulders." "There are uncertainties, but there are also consequences of going in too early or too late and they are gravely aware of this," he said.

Health adviser Bill Bowtell who helped lead Australia's response to the AIDS crisis has been highly critical of the Morrison government's response to coronavirus. He said state and federal governments must follow what Britain and New Zealand had done and enforce a nationwide shutdown. "It is time to do this in the national interest, and take control of the virus before it takes control of us," Professor Bowtell said. In updated advice on Monday, the Australian Health Protection Principal Committee said more than half our cases are still imported from overseas or their direct contacts. Sign up to our Coronavirus Update newsletter Get our Coronavirus Update newsletter for the day's crucial developments at a glance, the numbers you need to know and what our readers are saying. Sign up to The Sydney Morning Herald's newsletter here and The Age's here. Australia also has one of the lowest COVID-19 test positivity rates in the world and fewer than 20 people have needed ICU treatment so far.

"This suggests that we do not have as large a proportion of undetected cases in the population, as was likely the case in the USA, Italy and other countries and that our early detection and control work was effective." The AHPPC said, however, the recent rapid influx in imported cases and super-spreader events like a wedding in NSW, which saw 35 people later diagnosed with COVID-19, means more extreme measure must be taken in the coming weeks. "We are seeing evidence of non-compliance with these new measures and of people not taking this seriously," it said.