2 ms·

From the comic, you only need ~60% of contacts for it to be effective [1]. [1] https://science.sciencemag.org/content/early/2020/04/09/science.abb6936 https://

• ebg13 7y ago
  > only So... 200 million americans?
  • bhupy 7y ago
    You can't just compute 60% multiplied by US population, 20% of Americans are children. You also probably only need contact tracing in certain high risk geographies, urban centers, and a few suburban centers. 60% of the remaining can definitely fall under the "knowledgeable, willing, personally able (authorized to install app), technologically able (app works with their devices), and vigilant". Even if you don't hit 60%, you're still reducing R0 by enough that you can carefully start to re-open certain parts of the economy.