F8 Studio/ShutterstockContentsWhat is vaccine efficacy?How do we measure if a vaccine is effective? Zania Stamataki, University of Birmingham There was – rightfully – a lot of excitement when Pfizer and BioNTech announced interim results from their COVID vaccine trial. The vaccine, called BNT162b2, was reported to have an “efficacy rate above 90%”. This was soon … Continue reading Pfizer vaccine: what an ‘efficacy rate above 90%’ really means