Why is there so much general confidence warmer temps will reduce spread? Is it really warm temps = more daylight = more UV bouncing around breaking up virus particles in the air? Does it make any difference at all for the majority of folks who spend almost all waking hours inside?
I think there's probably an aspect of wishful thinking, and I certainly wouldn't say that there's anything like general confidence in the idea. Actually, I've only heard this stated as fact by politicians and similar; experts are mostly WAY more cautious about it.
it is because the warmer weather is what stopped SARS-COV in 2002 from spreading this far. the western world was lucky in that ignoring it the first time was an okay strategy. SARS-COV-2 is making its way around the globe right now and hopefully has the same limitations or this may get out of control. ignoring is the most dangerous option at this point. please watch this video by 3blue1brown https://www.youtube.com/watch?v=Kas0tIxDvrg a math professor in the US about the situation.
But maybe the main reason that SARS died out by the summer was not primarily because of the temperature but had more to do with the fact that it wasn't as nearly contagious and they were able to contain it with social distancing?
I don't know if there is such confidence among specialists, but among non specialists the arguments I have heard are based on assumed similarities with the common flu. These arguments may or may not apply , and there is still disagreement and unanswered questions on why the flu is seasonal:
I believe its something along the lines that when there is more moister in the air, the water droplets grab the floating particles and fall to the ground. Thus higher humidity often slows the impact of airborne virus, hence we have a flu season.
85 cases in Australia. And how many of those are imported?
In a binary sense, yes it “is spreading”. Even an R0 of 0.1 is “spreading”. But there is hardly enough data to say it is spreading widely in Australia.
The virus spread in summer/tropical vs winter/non-tropical regions is orders of magnitude different. But this is also not definitively causal. Just extremely highly correlated.
Yup, the counter to it is India. With almost all of the 43 cases imported even after more than 17000 tests seem to indicate that it's not spreading there (it could be a variety of factors including under-testing).
There does seem to be some secondary spread in Australia however this seems to be from close contact with people who have been overseas. We are a little late to the game having established effective screening and information sharing early On. There is a expectation that the next few weeks will show a marked increase in community spread.