Another week of COVID-19 restrictions as authorities hunt 'missing link'

NSW residents face an extra week of COVID-19 restrictions and uncertainty as authorities desperately hunt down the "missing link" to the state's latest mystery cases.

But there's more promising news on the vaccine front, as the state's long-awaited mass vaccination hub opens at Sydney Olympic Park, ready to administer up to 30,000 doses a week.

Restrictions were extended yesterday, with a small change to mask rules, despite no new cases being discovered.

Health authorities remain concerned about how an eastern Sydney couple in their 50s got sick, given contact tracers were yet to link back to a so-called "patient zero".

Investigators have linked their infections to a US case who entered hotel quarantine in Sydney on April 26 but still don't know how the virus jumped from that person to the Sydney couple.

"Despite extensive investigations to date, NSW Health has not identified how the initial case, the man in his 50s, was exposed to COVID-19, which suggests he acquired the infection through brief contact with a currently unidentified person who was infectious in the community," the department wrote in a statement.

From today, mask rules are no longer compulsory for customers shopping at retail stores but the workers themselves will still need to wear them.

Until 12.01am on Monday, May 17, home gathering are limited to 20 people, aged care residents are limited to two visitors a day and masks remain mandatory in indoor venues including public transport.

There's no singing allowed at indoor venues, where staff must be masked, and patrons must remain seated while drinking.

From 18,000 tests — down from over 22,000 the day before — there were six new cases of COVID-19 found in the state's quarantine hotels to Sunday.

A new health alert was earlier issued for a Woolworths in Sydney's eastern suburbs after an infected person visited the store.

Anyone who was at the Woolworths supermarket on the corner of Kiaora Lane and Kiaora Road in Double Bay last Monday, May 3, between 10.45am and 11am has been deemed a casual contact.