This all revolves around conservatives focusing on ARR instead of RRR numbers on vaccine efficacy. Here’s a description I found of the difference from another article:
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%).
Whole cell/virus vaccines have been around forever. Grog got some dirt on his hands while hunting ibex? Congrats, that’s a vaccine!