As vaccines are injected into millions of arms across the world, authorities are watching closely to see if there are any unexpected side effects.

And a higher than expected number of deaths in frail and elderly Pfizer vaccine recipients in Norway is drawing scrutiny.

The Norwegian Medicines Agency last week reported 13 people had died shortly after getting the Pfizer vaccine shot - all people over the age of 80 and all in nursing homes.

So how do we know if these deaths are to do with the vaccine, or whether they might have happened anyway? And if they do prove to be linked to the vaccine, what does this mean for the rollout?

Also on today's Coronacast:

* Australian Open participants in quarantine ahead of the tournament have tested positive to the virus - will they be cleared in time?

* Are there any side effects if you get a vaccine when you already have immunity to the virus?

* I increasingly meet people being suspicious about the vaccine. How do you talk to them?