COVID: NSW spreads inside (Shape of an emerging outbreak, part 2)

The original outbreaks in Sydney eventually died down, as specific public warnings, testing, tracing, monitoring, restrictions and quarantining incoming travellers slowly did the job.

But Sydney remains on the cusp of a renewed outbreak due to infection leakage from Melbourne, and it's still too hard for me to get a sense of whether new infections will settle down or not.  The recent Victoria mass outbreak breeds pessimism; yet the non-explosion in new infections plus the record amount of testing (see bottom of this article) gives room for optimism.

Over the past week or so, with intensive testing and contact tracing, the shape of the clusters is known.  New infections still hover around ten per day, with nearly all infections traceable to an existing cluster.

Despite the graphic given in the previous post, the actual defined clusters are slightly more nuanced.  If you read the news daily, you learn the immediate source of the infection, the source behind that (which is apparently what is represented in that graphic), and the warnings of locations those newly infected have attended and thus who should now get tested/isolate.

At this early stage, it would seem that nearly all new infections are due to prolonged exposure indoors.  That is, more than a few minutes spend indoors in the same space as someone who is infected.  That could mean a pub, a restaurant, a workplace, a gym, a church.  That's it, so far.  The implication, which is understandably not reported, is that outdoors exposure, brief exposure, public transport and shopping centre exposure, is not currently causing infections.


But it's early days in this second outbreak, and that could change.  Complacency is dangerous.  I warn my late teenagers to be cautious at shops, bus stops, public transport.  Masks - of any sort - fully recommended.

A major reason this virus has been so hard - and a good reason for all the above precautions - is that an estimated 40% of infectious people are asymptomatic.  Did you attend that funeral or this restaurant?  Then the official line is that you are urged to get tested and self-isolate.