The World Health Organization's chief scientist on Monday advised against people mixing and matching Covid-19 vaccines from different manufacturers, calling it a "dangerous trend" since there was little data available about the health impact.

"It's a little bit of a dangerous trend here. We are in a data-free, evidence-free zone as far as mix and match," Soumya Swaminathan said.

Watch the video to find out what experts have to say on the matter.