A second major vaccine breakthrough has sustained the rally in risk assets across global markets that began with Joe Biden's US presidential victory, and lent further credibility to optimism that economies will be dragged out of their COVID-19-induced hibernation.

US drug manufacturer Moderna announced its COVID-19 vaccine was close to 94.5 per cent effective, pushing the S&P/ASX 200 Index 13.9 points, or 0.2 per cent, higher to a nine-month high of 6498.2 on Tuesday.