The most interesting thing about the ARR metric is how hard it is to find. I never heard about it until recently.
The CDC explainers about the vaccines on their website don’t mention it at all. The paper I linked to above include some figures that make it easy to see the difference between ARR and RRR.
From what I can tell ARR takes into account the risk of getting the disease. Thus, if the chance of getting a disease is low, the ARR will be very low. Whereas it seems that the RRR informs one about the relative difference between the control group and the test group. Thus, RRR can be high even if an individual’s risk is very low.
Still not sure how ARR shows the benefit- or not - of vaccination.
The published data is understandable. One’s risk is diminished by a factor of ten.