The World Health Organization’s chief scientist 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. 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”, - Soumya Swaminathan told an online briefing.

She later clarified her remarks on Twitter, saying people should follow public health advice and not make their own decisions on vaccine mixing or taking additional doses.

Swaminathan said public health agencies can provide advice based on available data, but added that studies on mixing various vaccines are ongoing and that “immunogenicity and safety both need to be evaluated”.