Chief Health Officer Jeannette Young has conceded the missing link to establish how a family of five in west Brisbane became infected with coronavirus may never be known.

The virus, which was first detected in the community in an Indooroopilly State High School student, is known to have originated from a couple who travelled into Queensland from Sydney.

“It’s very possible we’ll never find that link.

“It could’ve been someone that got infected at the airport, or in hotel quarantine, or in the hospital, or in the community, and they could be one of that 20 per cent that doesn’t get symptoms.”

Dr Young said it’s very possible quarantine can be lifted for south-east Queensland on Sunday, even if the link is not identified.

The two most significant criteria outlined by officials for lockdown to be lifted are high testing numbers and for all cases to be in quarantine for the duration of their infectious period.

Queensland recorded 17 new locally-acquired cases today, with 16 linked to the west Brisbane outbreak.

Two cases had spent zero days active in the community while infectious, which Deputy Premier Steven Miles says is an early sign the lockdown is working.

The 17th locally-acquired case is a fully vaccinated Cairns pilot who guides ships through the Great Barrier Reef.

He is unlinked to the west Brisbane outbreak, with initial investigations indicating he became infected from a ship he worked with.

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