When NSW Premier Gladys Berejiklian started her press conference yesterday, she got straight to the point: NSW had detected a case of COVID in the community.

And as yet, there's no known source. The patient has not been overseas or interstate and has no known links to hotel quarantine.

He's also been infectious in the community for the last several days.

So as NSW Health tries to pin down where he might have got it, Coronacast asks how this mysterious case compares to other recent outbreaks.

Also on today's show:

* A study shows digital contact tracing apps can work

* Norman gets vaccinated

* If a person isn't vaccinated and contracts COVID, is the vaccine then administered to aid in recovery?

* Can I get the AstraZeneca vaccine now and Pfizer later to be even more protected?

* Can you advise me please on the recommended timing between a flu shot and the AstraZeneca shot?