I know this is a bit of a review, but it is still relevant. This is also another attempt to show the difference between absolute and relative risk. This difference is a huge difference and unacceptable that a drug was approved using relative risk instead of absolute risk.
Let’s say you are forced to take either Pill A or Pill B. Both of these pills are supposed to help you in fighting a disease that is currently spreading in your country. This disease can be deadly in some cases. Lucky for you, instead of flipping a coin, you have some data from 44,000 people that have flipped a coin before you to help you with your decision. These 44,000 people signed up to to take Pill A or Pill B with the flip of a coin, they are what we call Guinea Pigs. Here is the data 22,000 people took Pill A and within the next 6 months, 5 had heart attacks, 1 died from the disease it was supposed to help prevent, and 20 people died of all causes. On the other hand 22,000 people took Pill B. Of the 22,000 people that took Pill B within the next six months, 1 person died of a heart attack, 2 people died from the disease it was supposed to prevent, and 14 people died of all causes.
Which pill are you taking? I think most people looking at that data would take Pill B. I will mention now that Pill A had 8 cases of the disease it was supposed to prevent in the 2.5 months after taking it, and the Pill B had 162 cases of the disease it was supposed to prevent.
I am sure by now you have figured that Pill A is the vaccine and Pill B is a saline solution that is known to be inert. This is were the relative risk vs. absolute risk comes in. In the 75 days after taking the pills, Pill A had 8 cases of the disease compared to the 162 cases in the group of people that took Pill B. This is a relative effectiveness of 162/170 or 95%. This sounds good, but is so misleading. Let’s look at absolute effectiveness, 8/22,000 or 0.036% chance of catching the disease in the 75 days after taking the pill for the Pill A people. It is 162/22,000 or 0.74% chance of catching the disease for the Pill B people over those same 75 days.
Let’s look at death from this disease. Pill A, 1 death compared to 2 in the Pill B group. These 2 deaths are a 100% increase over 1. This sounds very effective. However, it is 2/22,000 and 1/22,000 for a 0.09% chance of dying with Pill B and a 0.005% with Pill A.
Let’s use relative effectiveness for death from heart attacks. There was 1 heart attack death in the Pill B group, and 5 deaths from heart attack in the Pill A group. This is a 500% higher chance of having a heart attack for the Pill A group. The Pfizer press release doesn’t use relative chance when giving us heart attack data.
Let’s look at all cause mortality. Chance of death from all causes in Pill A is 42% higher than Pill B.
Which Pill are you taking? Keep in mind we know the long term effects of saline, but we do not yet know the long term effects of Pill A yet. It should also be mentioned that in the clinical trial the data presented starts 14 days after second shot for both groups. This means that any deaths, heart attacks, cases, or other side effects are not counted if they happened immediately after the first or second shot. This means the relative numbers are probably worse. We won’t find this out for 75 years. These two groups were supposed to remain Guinea Pigs for two years, but after 6 months the study was ended, so we won’t find out any more info on longer term effects.