As we can see from what's happening around the country, the Delta variant has changed the game when it comes to controlling the spread of coronavirus.

It seems unlikely Sydney will ever regain control, and there are major battles in ACT and Melbourne.

The Delta variant has surprised virologists with how it popped into existence and how it has so rapidly taken over.

But not all is lost. On today's Coronacast, the three scenarios of where we could be headed next.

Also on today's show:

* A worrying risk of double infections in children

* What's going on with NSW contact tracing?

The ACT is in a week-long lockdown, joining many other regional NSW local government areas and Melbourne on their journey to stopping Delta.

The ACT Chief Health Officer Dr Kerryn Coleman says as yet there's no known link back to known Sydney cases, and genomic information will be available today.

And Victoria yesterday recorded two cases in hotel quarantine who had arrived on a plane from Sydney.

So on today's Coronacast, with the virus continuing to push outwards, can anything be done to stop it?

Coronacast is taking a small break. We'll be back on Wednesday 18th August!

It sounds impossible: the complete and utter annihilation of the SARS-CoV-2 virus, worldwide. Almost too silly to even mention.

Well, according to a research paper published in the British Medical Journal's Global Health it's something that - while very difficult - may be possible.

The article says that COVID-19 eradication might be slightly more feasible than for polio, which was almost eradicated from the world.

So on today's Coronacast, is it possible? And what else is the research telling us about COVID-19?

If you've been following the daily COVID-19 case numbers in Sydney, you'll know the numbers are steadily increasing.

So far, despite a lockdown lasting weeks and weeks, the NSW Government's restrictions have not yet managed to bend the curve.

The NSW Premier Gladys Berejiklian says the fight against Delta means the old way of doing things needs to be revisited and it needs a different approach.

So on today's Coronacast, does Delta change things? And if so, how?

Also on today's show:

* Research finds infections were three times lower in people who were fully vaccinated

The nation's vaccine goals are all about getting 70 to 80 per cent of people aged 16 or more vaccinated.

But that still leaves large numbers of people who aren't vaccinated, and the vast majority of them are kids.

So what's the plan for kids when the country starts opening up and what do we know about when vaccines might be trialled and approved for children?

Also on today's show:

* If two doses of either COVID-19 vaccines offer around 90 per cent protection against hospitalisation and death from the virus, that is still a 1 in 10 chance of being hospitalised if I get the virus. I thought that without being vaccinated the hospitalisation rate was around 1 in 10. I must be missing something here. Can you please explain?

* More on the time gap between AstraZeneca shots in different states.

It seems short, sharp lockdowns are the new black, and are now being used regularly down the east coast of mainland Australia.

Brisbane's short, sharp lockdown lifted yesterday, but Victoria, Cairns and parts of regional NSW have all entered one since last week.

So are we going to see large parts of Australia enter and exit lockdown until enough of us are vaccinated?

Also on today's show:

* Why you may be better covered by getting AstraZeneca today, rather than waiting for another option

* You spoke about a study that indicated that Pfizer is 88 per cent effective at preventing symptomatic disease. Does that also mean that the remaining 12 per cent means that even if you do get symptoms they are likely to be far less severe?

As Australia's march towards higher and higher rates of vaccination rolls on, more and more ideas are being thrown around to try and convince eligible people to get the jab.

Yesterday, fruit and vegetable processor SPC became the first Australian company to mandate vaccines for all onsite staff and visitors.

It raises the question: if SPC can do it, why aren't we seeing similar mandates for healthcare, aged care and child care workers?

At the moment, the answer is ... complicated, as you'll hear on today's Coronacast.

Also on today's show:

* Kids and long COVID. Good news!

* How effective are masks? I've read 80 per cent, then heard someone say 40 per cent. What's the latest research?

* Norman has often said that 80 to 90 per cent of people don't pass on the virus. I don't have any special data on this but that *feels* way too high. Is it?

With the coronavirus outbreak in NSW not yet showing many signs of getting better, and another outbreak in Queensland growing by the day - it's all a bit depressing

But there is good news: the vaccine program is finally speeding up and with every passing day thousands more people are vaccinated against COVID-19.

So on today's Coronacast, if very high vaccination rates can continue in NSW, a turn around might not be as far away as we fear.

Also on today's show:

* The end of winter will coincide with predicted population vaccination goals. How do we distinguish between the seasonal aspect of COVID and vaccine effect?

* Why is forcing over 60s to have AstraZeneca not being recognised as discrimination and agism?

* I am 61, when will I be eligible for the Pfizer jab?

* Can we get more Pfizer doses by using the remaining amount at the end of each vial?