As the world celebrates advances in vaccines against the novel coronavirus, a top WHO expert warned in an interview with AFP that public distrust risked rendering even the most effective treatments useless against the pandemic.

“A vaccine that sits in a freezer or in a refrigerator or on a shelf and doesn't get used is doing nothing to help shorten this pandemic,” said Kate O'Brien, director of the World Health Organization's immunisation department.

US pharmaceutical giant Pfizer and its German partner BioNTech announced Monday that their prospective vaccine had proven 90 per cent effective in preventing Covid-19 infections in ongoing final phase trials involving more than 40,000 people.

O'Brien hailed the interim results as “extremely important”, and voiced hope that preliminary data from a handful of other candidate vaccines in similarly advanced trials would come through soon.