I think at this point all the 'efficacy' numbers given by drug companies for the various vaccines on the market are: relative risk reduction of hospitalization or death.
Not uninteresting per se, but would be even more interesting if paired with the absolute risk number [1].
* positive PCR tests
* showing symptoms
* hospitalization
* death
I share kube-system's frustration with the media glossing over those details quite often.
Here in Germany, there were numbers thrown around such as the mRNA vaccines being 90%+ effective, and the AstraZeneca being only in 60ies or 70ies (which was likely based on PCR tests). Which made many Germans hesitant to get that vaccine.
Turns out, AstraZeneca prevents hospitalization at a roughly 90% effectiveness rate (recent numbers from England, don#t have link ready right now), which sound much better than 65% number.
https://www.cidrap.umn.edu/news-perspective/2021/05/real-wor...
[1] Quoting the article's explanation of AAR vs RRR: "The vaccine and placebo groups in Figure 1 each have 100 randomly assigned individuals with no history of infection, and an event is defined as the incidence of infection among all individuals during the course of the trial. The percentage of events in the vaccine group is the experimental event rate (EER) or the risk of infection in the vaccine group (1/100 = 1%), and the percentage of events in the placebo group is the control event rate (CER) or the risk of infection in the placebo group (2/100 = 2%). Absolute risk reduction (ARR) is the disease risk difference between the placebo and vaccine groups, i.e., the CER minus the EER (2% − 1% = 1%). The ARR is also known as the vaccine disease preventable incidence (VDPI). Relative risk reduction (RRR) or vaccine efficacy (VE) is the reduced risk from vaccination, the ARR or VDPI, relative to or divided by the risk in unvaccinated individuals, the CER (1%/2% = 50%)".
Sure, ARR is more interesting for risk/cost benefits analysis. So much so that it is part of the official FDA guidelines expressed in this document ("Communicating risks and benefits: An evidence based user guide" [1]).
"Another statistical choice is between reporting relative or absolute risks. Because there is no way to infer the latter from the former, absolute risks are always more informative. Doubling a risk means very different things if that entails going from 10% to 20% or from 0.001% to 0.002%.Even when they contain the same information, different summaries can highlight different perspectives, hence bias choices."
Besides, if you compare the ranks of the main vaccines in each stat, you can see that it is not the same information expressed differently:
ARR: AZ 1.3%, Moderna 1.2%, J&J 1.2%, 0.84% Pfizer RRR: 95% Pfizer, 94% Moderna, 67% J&J, 67% AZ
That could still mean several different things.
I'm not questioning whether or not any of them are effective enough to be useful. I got the first one I could. I'm questioning whether or not the comparisons that others are making are meaningful.