A quick walkthrough of how one might translate a stat like this into an rough estimate of vaccine efficacy. Not to be used as a substitute for proper work done by e.g., Public Health England, but just to check a first impulse of: 40% vaxxed? Sounds like a lot. Do they work? (1/5) https://t.co/LW1bKerNJI

— Paul Mainwood (@PaulMainwood) July 20, 2021