A variant of Covid-19, which has triggered a snap lockdown in greater Brisbane and prompted the federal government to announce new testing requirements for travellers, may become the dominant variant circulating globally, virology and infectious diseases experts say.
The Queensland premier, Annastacia Palaszczuk, announced a three-day lockdown of greater Brisbane after a hotel quarantine worker was infected with the variant known as B117. With 79 close contacts identified, the case has health authorities concerned. While the variant has previously been detected in returned travellers isolated in hotel quarantine, it has not yet spread into the Australian community.
Dr Stuart Turville, an associate professor in the immunovirology and pathogenesis program at the Kirby Institute, said while it was initially unclear whether the B117 was more infectious, there was now enough evidence to determine it was more transmissible.
“One of the things that concerns us is the amount of changes in this variant, and that means it becomes a black box, an unknown entity,” Turville said. “When you have this unknown, it’s best to get a lockdown done and get it done quick, and you can then keep it short and sweet. If I was in charge in Queensland I’d be doing the same until we get a better handle of what we are dealing with.”
The B117 variant was first found in London in September, and genomic sequencing was completed in October. By December, UK health authorities said it was clear mutations in the spike protein had emerged rapidly, and that B117 was spreading at a concerning rate. A December report from the UK’s New and Emerging Respiratory Virus Threats Advisory Group found the rate of transmission of the B117 variant was 71% higher than for other variants.
The B117 variant is now the dominant strain in some parts of England.
Turville said such changes in the virus were not unexpected. There was another variant identified earlier on in the pandemic, known as the D614G variant. It was also found to be more transmissible than the original virus strain, and D614G had since become the dominant variant globally.
“And I’d say this is just another case similar to the D614G situation,” he said.
Many countries have closed or restricted their borders to travellers from the UK in an effort to prevent the variant from entering. On Friday, the prime minister, Scott Morrison, said 80% of Australians registered to return from overseas were in countries where the B117 variant had been found. After a meeting of national cabinet, he announced a negative Covid-19 test must be recorded by all people seeking to travel to Australia prior to departure, and that international arrival numbers to New South Wales, Queensland and Western Australia would be halved.
The director of infectious diseases and immunology at Menzies Health Institute Queensland, Griffith University, Prof Nigel McMillan, said there were now two strong pieces of evidence that had proven the B117 variant was more infectious, as opposed to just spreading more quickly due to a lack of public health measures in the UK.
“When you grow this virus in the lab you seem to get more virus out than you normally would, so it seems to grow more quickly,” he said. “The other evidence is that the R-nought number – how many people will catch the virus from one person infected – has gone up from 1.1 to 1.5 for this strain, so people with this strain are more infectious.
“But this is what viruses do. They strive to be their most efficient selves. And this strain is now responsible for more than three-quarters of the cases in greater London.”
He said whichever variant transmitted most effectively “would come to dominate”.
“This is probably why Queensland has taken the sensible move into lockdown,” McMillan said.
“Because we just know from experience that if you get the thing early it’s so much easier to control, compared to trying to control it later as was the lesson in Melbourne. Once this thing gets out and about it just becomes so much harder to bring under control.
“In fact I would suggest that we may have to extend the lockdown if we get some community cases of this popping up over the next few days.”
The US Centers for Disease Control said there was no strong evidence yet that the B117 strain is more deadly or severe, or that tests or vaccines would prove ineffective. B117 also seems to infect people aged under 20 at a higher rate than other variants.
But the rapid spread is overloading health services in the UK. A professor of structural biology with the University of Oxford, Jim Naismith, told the Science Media Centre: “It is not really possible to overstate how serious this new strain is.
“The National Health Service is under serious strain and without a change this will get worse. January and early February will be difficult,” he said. “If we fail to reduce the spread of the new strain, then we are likely to overwhelm the NHS, the consequences of this would be dire.”
The president of the Australian Medical Association, Dr Omar Khorshid, said the same could not be allowed to happen in Australia.
“This UK strain appears to be a greater risk of breaking out of hotel quarantine, and then spreading quickly to outrun and overwhelm our last lines of defence – physical distancing and testing and tracing,” he said.
“The three-day lockdown across Brisbane and other south-east Queensland regions may not be popular. Nor may the stricter quarantine rules, and the testing of passengers before they board a plane to Australia. But we have seen in the past that decisive action, taken early, is the best way to stop this wicked enemy.”