Pretty much since coronavirus emerged, people have been worried about it mutating, but in the past month or so reports of strains that are particularly contagious have caught the public's attention and begun to guide public policy.

What makes these strains different to earlier mutations? Is the so-called UK strain really 70 per cent more transmissible? What does this mean for vaccines, and why are similar mutations popping up in virus strains in distant parts of the world?

Norman Swan and Tegan Taylor put these questions and more to virologist Professor Edward Holmes from the University of Sydney in today's Coronacast.