# The cr.yp.to microblog: 2020.03.30 01:21:31

2020.03.30 01:21:31 (1244404348697710593) from Daniel J. Bernstein, replying to "🔴@pdfkungfoo@meteo.social🐝🔋 #YesToNoCovid (@pdfkungfoo)" (1244398199659511810):

Daily increase is the bottom line, but the real importance of R0 is as an action item. If R0 is, say, 3, and if we can reduce the number of people we transmit to by a factor above 3 through widespread use of masks and hand-washing and telecommuting, then we win the COVID-19 war.

### Context

2020.03.24 05:57:12 (1242314501854130177) from Daniel J. Bernstein:

Even within the paper's focus on distancing, the paper's quantitative conclusions start by assuming that distancing reduces R0 by _at most_ 60%. The paper claims, citing (3), that this is what China's distancing did. (3) does _not_ say this; it says that China did _at least_ 60%.

2020.03.30 00:35:24 (1244392742752522240) from "🔴@pdfkungfoo@meteo.social🐝🔋 #YesToNoCovid (@pdfkungfoo)":

Even if (assumed) R0=2 is reduced by only 30% and putting daily growth from (assumed) 100% down to 70% - that‘s a HUGE single contribution to #FlattenTheCurve!
In 21 days you’d go from 1 infected person to 70.000 instead of going to 2,1 million.

2020.03.30 00:51:44 (1244396853212221440) from Daniel J. Bernstein, replying to "🔴@pdfkungfoo@meteo.social🐝🔋 #YesToNoCovid (@pdfkungfoo)" (1244392742752522240):

Small changes in R0 have an exponential effect, yes, but R0=2 doesn't mean 2x every day: it means you're transmitting to 2 people on average during your infectious period after your incubation period. Even in crowded city with higher R0, hopefully incubation takes multiple days.

2020.03.30 00:57:05 (1244398199659511810) from "🔴@pdfkungfoo@meteo.social🐝🔋 #YesToNoCovid (@pdfkungfoo)":

I know, but assumed you‘d understand the idea and use your power of Twitter reach to spread the understanding. I also mentioned „assumed“ daily growth. Replace „days“ in my tweet by „infectious period“ and we are there...