Australia on Thursday reinstated social distancing restrictions across greater Sydney as officials scrambled to trace the missing transmission links in ‘msytery’ Covid-19 cases related to an Indian variant of the coronavirus.

The New South Wales government limited household gatherings to 20 guests and restricted ‘aged care facility’ visitors to two per resident keeping in mind gatherings over the upcoming weekend for annual Mother’s Day celebrations.

Masks have been made mandatory on public transport and indoor venues. All restrictions will come into effect from 5 pm (local time) and will continue till Monday morning. Around 5.3 million people reside in the country’s biggest metropolitan area.

“We believe this is a proportionate response to the risk we have ahead of us,” NSW Premier Gladys Berejiklian told reporters, according to news agency Reuters.

The stringent measures were put in place, extending to Sydney’s neighbouring regions of Wollongong, the Central Coast and Blue Mountains, after the detection of the Covid-19 infection in a 50-year-old man, who passed on the infection to his wife.

The case, which was the first local transmission in NSW in over a month, stumped health officials as the man had no known links to high-risk people or jobs.

“Subsequent testing revealed that the person was infected with a new variant that was first detected in India and genomic sequencing linked the case to a traveller who returned from the United States,” NSW Chief Health Officer Kerry Chant said, adding that there was no clear link of transmission between the two people.

“We can’t find any direct link between our case, so what we’re concerned about is there is another person that is as yet unidentified that infected our case,” Chant added.

This is probably the first time authorities have reported the local transmission of an Indian variant of the virus in Australia.