There are fears a 'double-mutant' coronavirus strain has leaked into the community despite NSW reporting zero new cases on Friday.
The promising result comes after Premier Gladys Berejiklian said on Thursday a woman tested positive for the virus after it was revealed a day before her husband, a man in his 50s, also returned a positive result.
Chief Health Officer Dr Kerry Chant said the two tested positive for the B.1.617 mutation, according to the Sydney Morning Herald.
Despite the promising number of cases on Friday, there are fears the strain could still be circulating in the community as there is a missing link between the man and the original source which was traced to an overseas traveller in a quarantine facility.
University of Sydney virologist Megan Steain told The Sydney Morning Herald the strain could potentially be transmitted at a more rapid rate than past strains.
"The rate at which (the variant) seems to be spreading in India suggests that it may be transmitted more efficiently than earlier variants of the virus," she said.
"Quickly performing contact tracing, testing and isolating people potentially exposed individuals will also be key to preventing spread in the community."
The strain of virus, also known as an Indian variant, is referred to as a "double mutant" as it has two mutations within the one strain.
University of Cambridge's Public Health and Microbiology Professor Professor Sharon Peacock said in a statement it first emerged in October 2020.
"India has submitted the most B.1.617 genomes, following in frequency by UK and the US," she said.
"India is currently witnessing a surge in Covid-19 cases. The question is whether this is associated with the variant, with human behaviour – the presence of large gatherings, lack of preventative measures including hand washing, wearing masks and social distancing – or whether both are contributing.
"It is not clear at the present time whether B.1.617 is the main driver for the current wave."
Professor Peacock said B.1.617 had been described as a double mutant, but resisted using the term.
"This term is used to refer to two mutations in spike (E484Q and L452R) but is inaccurate, has no specific meaning and should be avoided."
Australia to resume India flights
The variant has now reached at least 17 countries including Britain, Switzerland and Iran, prompting some governments to close their borders to people traveling from India.
Australians in India who fail a pre-flight coronavirus test will be banned from boarding when rescue planes restart from May 15.
Prime Minister Scott Morrison on Friday announced the travel ban would end on its planned expiry date, following a fierce backlash against the harsh measures.
"The pause that we put in place for travellers coming back from India is working," he told reporters in Newcastle.
There will be three flights this month to bring back the most urgent cases with 900 vulnerable citizens and permanent residents stranded in India.
All arrivals will be quarantined at the Northern Territory's Howard Springs mining camp where capacity is set to increase to 2000 beds.
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