SMH.com.au reporting:
Almost entire second wave in Victoria linked to returning travellers
By Michael Fowler
Genomic sequencing shows more than 99 per cent of Victoria’s second wave of coronavirus can be linked to returned travellers in hotel quarantine, the inquiry into Victoria’s hotel quarantine program has heard. Professor Ben Howden, head of the Doherty Institute’s genomic sequencing unit, is now giving evidence at the inquiry into Victoria’s hotel quarantine program.
Chief Health Officer Professor Brett Sutton has previously said their genomic sequencing showed most, if not all, of Victoria’s second wave of coronavirus, could be linked to hotel quarantine leaks, though the government has refused to release the sequencing report.
Interestingly, Professor Howden said the genetic signature of COVID-19 has the equivalent of 30,000 letters in a row. Genomic sequencing attempts to identify those letters and put them in order. Experts can then compare the different signatures - or strains of the virus - to see if they are the same.
In the case of hotel quarantine, experts can compare the genetic signature of COVID-19 in a security guard to the genetic signature in another person in Melbourne weeks later. If they are the same, that indicates the other person's virus can be linked to the security guard, indirectly or directly.
Explaining the genomic sequencing provided to the Victorian government, Professor Howden said from the start of June, three strains of COVID-19 have been detected, each imported from overseas. That indicates coronavirus was leaked into Victoria from at least three breaches from quarantine hotels, via security guards and workers
“What I could say, a high-level statement would be, that over 99 per cent of all current cases in Victoria for which we have genome sequences are derived from [those three sequences],” Professor Howden said.
“Such that essentially all current cases, bar a few, are from those [three sequences]." Chief Health Officer Brett Sutton and Premier Daniel Andrews have previously said “at least a significant portion” of Victoria’s second wave is due to hotel quarantine breaches.
Professor Howden, head of genomic sequencing at the Doherty Insitute, said his unit had analysed 46 per cent of Victoria’s total cases up to July 23. He confirmed their data showed the strains of COVID-19 from Victoria’s first wave had died out by late May and early June, when the second wave began to spread.