Why you can t compare Covid-19 vaccines

What a vaccine s "efficacy rate" actually means. Sign up for our newsletter: http://www.vox.com/video-newsletter In the US, the first two available Covid-19 vaccines were the ones from Pfizer/BioNTech and Moderna. Both vaccines have very high "efficacy rates," of around 95%. But the third vaccine introduced in the US, from Johnson & Johnson, has a considerably lower efficacy rate: just 66%. Look at those numbers next to each other, and it s natural to conclude that one of them is considerably worse. Why settle for 66% when you can have 95%? But that isn t the right way to understand a vaccine s efficacy rate, or even to understand what a vaccine does. And public health experts say that if you really want to know which vaccine is the best one, efficacy isn t actually the most important number at all. Further reading from Vox: Why comparing Covid-19 vaccine efficacy numbers can be misleading: https://www.vox.com/22311625/covid-19-vaccine-efficacy-johnson-moderna-pfizer The vaccine metric that matters more than efficacy: https://www.vox.com/22273502/covid-vaccines-pfizer-moderna-johnson-astrazeneca-efficacy-deaths The limits of what vaccine efficacy numbers can tell us: https://www.vox.com/21575420/oxford-moderna-pfizer-covid-19-vaccine-trial-biontech-astrazeneca-results Vox.com is a news website that helps you cut through the noise and understand what s really driving the events in the headlines. Check out http://www.vox.com. Watch our full video catalog: http://goo.gl/IZONyE Follow Vox on Facebook: http://goo.gl/U2g06o Or Twitter: http://goo.gl/XFrZ5H