World Health Organization’s chief scientist Soumya Swaminathan on Monday advised against mixing and matching coronavirus vaccines from different manufacturers, calling it a “dangerous trend”, reported Reuters. “We are in a data-free, evidence-free zone as far as mix and match,” Swaminathan said at an online briefing. “It will be a chaotic situation in countries if citizens start deciding when and who will be taking a second, a third and a fourth dose. There are studies going on [on mix and watch], we need to wait for that.”