This time last year, Australia's vaccination program was getting underway and many were coming forward for their first or second shots.

But Australia's haven't embraced the third dose as quickly or in as large numbers.

The third dose is vital for the best protection against disease, and is recommended for the majority of Australians.

So why aren't people coming forward as quickly?

Also on today's show:

* Is it possible that we may have caught COVID without realising it?

* Are there instances of assumed second COVID infections that are actually just relapses?