In risk estimation, knowing the absolute risk reduction (the number that actually matters the most) is crucial.
The Absolute Risk Reduction (ARR), which is the difference between attack rates with and without a vaccine, considers the whole population.
Absolute Risk Reduction:
1·3% for the AstraZeneca–Oxford
1·2% for the Moderna–NIH
1·2% for the J&J
0·93% for the Gamaleya
0·84% for the Pfizer–BioNTech vaccines
If your risk of getting a certain disease is reduced by only about 1%, is the vaccine worth it?
From the Lancet article: “Vaccine efficacy is generally reported as a relative risk reduction (RRR). It uses the relative risk (RR)—ie, the ratio of attack rates with and without a vaccine—which is expressed as 1–RR. Ranking by reported efficacy gives relative risk reductions of 95% for the Pfizer–BioNTech, 94% for the Moderna–NIH, 90% for the Gamaleya, 67% for the J&J, and 67% for the AstraZeneca–Oxford vaccines. However, RRR should be seen against the background risk of being infected and becoming ill with COVID-19, which varies between populations and over time. Although the RRR considers only participants who could benefit from the vaccine, the absolute risk reduction (ARR), which is the difference between attack rates with and without a vaccine, considers the whole population. ARRs tend to be ignored because they give a much less impressive effect size than RRRs: 1·3% for the AstraZeneca–Oxford, 1·2% for the Moderna–NIH, 1·2% for the J&J, 0·93% for the Gamaleya, and 0·84% for the Pfizer–BioNTech vaccines.”
https://www.thelancet.com/journals/lanmic/article/PIIS2666-5247(21)00069-0/fulltext