Many countries are using the approach of mixing vaccine doses from different manufacturers. What do we know about the safety and efficacy of this approach? What does the evidence tell us about using a fraction of the vaccine dose ? Dr Katherine O’Brien explains in Science in 5 this week. Closed Captioning is available for Science in 5 in several languages on YouTube:Spanish,Portuguese,Thai,Nepali,Maithili,BahasaandJapanese.