How did Brisbane's COVID-19 quarantine hotel breach happen?
Authorities are scrambling to determine how a flight attendant contracted COVID-19 from a person staying on a different floor of hotel quarantine in Brisbane. The case of the woman who tested positive after leaving 14 days of hotel quarantine, during which she returned multiple negative tests, has authorities scratching their heads. Queensland COVID-19 snapshot: Confirmed cases so far: 1,670  Confirmed cases so far: 1,670 Deaths: 7  Deaths: 7 Tests conducted: 2,794,129  Tests conducted: 2,794,129 Active cases: 32 Latest information from Queensland Health. Genome sequencing has confirmed the woman caught the virus in hotel quarantine and not from a passenger on the flight to Australia. They believe she contracted it from a member of another airline's cabin crew who was staying on a different floor of the hotel and who flew in from another country. Virologist Nigel McMillan of Griffith University calls it "a mystery" that could have a "simple" explanation. We asked Professor McMillan to address some of your questions. The woman arrived in Brisbane from Portugal and went immediately into mandatory hotel quarantine, where she was tested three times. She left quarantine at 9:00am on Saturday and, in accordance with Queensland Health requirements for international flight crew, underwent a further test later that day. Professor McMillan said transmission could be down to something as simple as a door handle or lift button. ( Supplied: Griffith University  This is when she tested positive. A contact tracing effort was launched, with multiple locations in Brisbane named as exposure sites, including the DFO shopping complex near the airport. Professor McMillan said while there had previously been instances of spread across the same hotel floors, he could not recall another case of infection moving between floors. "It could have been incidental  a door handle, a lift button, something as simple as that," he said. "It could potentially be that there's a ventilation issue between those two floors [or] it could be via an intermediary, that could be possible. "These are all things that Queensland Health will be looking at." Professor McMillan said there was one other unlikely possibility: "It could be that she got the same virus well before her travel and she's just a very late developer, but I don't think that's the likely explanation." Initial investigations indicated the woman had the more infectious Delta variant of COVID-19. But subsequent genome testing revealed she has the B117  or Alpha strain  of the virus, known as the UK variant. Professor McMillan said Queenslanders are lucky the woman does not have the more contagious strain, because this means the virus's reproduction rate is lower. "If we look at the infectivity of the UK strain, we use this figure called R0 (R-nought)," he explained," he said. "Essentially, what it means is if one person has it, they will pass it on to about four other people. "The original Wuhan strain is roughly two [and] in the new strains, the Delta-Kappa strains from India, that figure is somewhere between six and eight. "So, we're lucky in the sense that it could have been worse  but it's still highly infectious." Not necessarily. The virus has undergone multiple mutations since the beginning of the pandemic, often resulting in more contagious or deadlier forms of the virus. Professor McMillan said he does not feel Australia needs to consider extending quarantine to 21 days. ( ABC News: Ben Harris  Professor McMillan said the hotel quarantine system has been working "very well" based on the latest data, but there were drawbacks. "We've seen 350,000 people [go] through the system and less than 20 escapes [of the virus]," he said. "But that has resulted in two lockdowns in Brisbane and a short lockdown in Western Australia and longer lockdowns in Melbourne." Professor McMillan said if Australia wanted to bring back international students and expats, larger quarantine facilities similar to those at Howard Springs in the Northern Territory would be required. "We know that 95 per cent of people will be positive by day 14," he said. "Given the success of the program in terms of the figures, the cases of people who have become positive after testing negative is quite small, so I don't think we need to go to 21 days [quarantine] at all." Singapore and Hong Kong recently extended their quarantine periods from 14 days to 21 days. The Commonwealth has recently approved a purpose-built quarantine facility to be built in Melbourne  in addition to one that has been operating in the Northern Territory. However, a Queensland proposal has been dismissed by Prime Minister Scott Morrison on multiple occasions. Experts have previously warned that aerosol transmission of COVID-19 could be the "gap" in Australia's quarantine system. After Brisbane's Hotel Grand Chancellor cluster, occupational hygienists suggested the possible cause of the outbreak was "aerosol spread or airborne transmission" between rooms of the quarantine hotel. Ventilation and the indoor air quality of the hotel rooms were also scrutinised and touted as potential culprits in spreading the virus. It is still too early to tell. Professor McMillan said the virus could be detected within five days of exposure, on average, while symptoms could be detected at three days. I think two days is probably fairly short [but it] depends on the sensitivity of the test," he said. "Ultimately, the people at the DFO on Saturday, they want to get tested today, tomorrow, Wednesday.  For now, Queensland Health have released a list of exposure zones and anyone who visited these locations is being urged to get tested immediately. So far, no community transmission has occurred  but more will come to light as authorities look further at this specific case.