positive rate,, percentage positive, positivity rate 都是同一个东西，下面c

copy一段解析

https://publichealth.jhu.edu/2020/covid-19-testing-understanding-the-percent-positive

The percent positive is exactly what it sounds like: the percentage of all coronavirus tests performed that are actually positive, or: (positive tests)/(total tests) x 100%. The percent positive (sometimes called the “percent positive rate” or “positivity rate”) helps public health officials answer questions such as:

• What is the current level of SARS-CoV-2 (coronavirus) transmission in the community?
• Are we doing enough testing for the amount of people who are getting infected?