When you're scheduled in for your COVID vaccine, depending on your age you'll get two doses of either AstraZeneca or Pfizer.

But what if you had one brand, and for your secord shot you had the other?

Well, researchers have been looking at this for a whole bunch of reasons - a main one being it makes rolling out the vaccines simpler.

And on today's Coronacast, early results suggest that mixing brands might also make the vaccines work better too.

Also on today's show:

* Do blood clots only happen after the first dose of the vaccine, or are they also happening after the second?

* When people talk of a booster vaccination does it simply mean another jab of exactly the same ingredients as in the first injection?

And we are joined by special guest Professor Paul Monagle from the University of Melbourne, to talk about the possibility of using the common drug heparin as a short term protective shield to stop you getting COVID-19.