I think you mean ARR vs RRR. But you didn't stumble

Posted on: October 13, 2021 at 23:38:31 CT

upon something new.

Here is a for dummies guide since you need it.

https://www.reuters.com/article/factcheck-thelancet-riskreduction-idUSL2N2NK1XA

According to medical experts at Meeden’s Health Desk here the RRR tells us how much the risk of infection is “reduced in the test vaccine group, compared to a control group who did not receive the test vaccine.” The RRR, or efficacy, tells us "how well the vaccine protects clinical trial participants from getting sick or getting very sick.”

Meedan Health Desk exemplifies how the ARR “will always appear low” as it depends on the event rate.

“Let’s say a study enrolled 20,000 patients into the control group and 20,000 in the vaccine group. In that study, 200 people in the control group got sick and 0 people in the vaccine group got sick. Even though the vaccine efficacy would be a whopping 100%, the ARR would show that vaccines reduce the absolute risk by just 1% (200/20,000= 1%). For the ARR to increase to 20% in our example study with a vaccine with 100% efficacy, 4,000 of the 20,000 people in the control group would have to get sick (4,000/20,000= 20%).”l