First I've heard of "Infectivity Rate"

[Laura PourMeADrink]

From local central TX newspaper...

District reported Thursday that four more residents had tested positive, bringing the local case count to 117, with 18 cases active. The increase comes as the statewide “infectivity rate,” the average number of people each infected person spreads the disease to, recently climbed to the fifth highest in the nation

[htuttle]

1. "the average number of people each infected person spreads the disease to"

Sounds like r0.
https://en.wikipedia.org/wiki/Basic_reproduction_number

[Laura PourMeADrink]

2. Yes, thanks, but still don't understand how anyone

Even knows that. Especially in TX where trump and abbott are friends and all numbers suspect.

[Freethinker65]

3. Look at doubling times for hospitalizations and deaths