Anju
Well-Known Member
This is a new one to me. An article in the Lancet saying that absolute risk reduction figures should be reported to give a fuller picture of vaccine effectiveness, posted by anti vaxxers because the ARR figure is around 1% and that must be bad because they're telling up its 90+% effective.
I'm clueless about relative risk reduction and ARR so had to Google the terms and their use relating to vaccines. Tried explaining to the poster though not entirely sure I'm correct. Kept repeating the same thing in different ways but the antiva poster was sticking to their interpretation. Interested to know if the two, of many, replies below are correct.
"They're just saying it's useful but not that it invalidates the RRR percentage. If you have 2 groups of 20,000 people and 200 of the unvaccinated get covid and none of the vaccinated do then the RRR is 100% but the ARR would be 1%. Whatever the ARR is the RRR stays the same. It's looking at a group outcome but the ARR is looking at individual risk. If only 1% of the population are catching covid the benefit, or reduction in risk is low as you're unlikely to catch covid"
"I think you're not getting what absolute risk reduction means. I didn't until I read the article and looked it up.
In the Pfizer trial there were 21,720 people who got two doses of the vaccine, and 21,728 got two doses of placebo. Study was two months long. 8 vaccinated and 162 placebo group tested positive for covid. That means the risk of COVID-19 in the vaccinated group was 8/21,720 = 0.037%, and the risk in the placebo group was 162/21,728 = 0.745%. The ARR is the difference in risk between the two groups. In this case it would be = 0.745% – 0.037% = 0.708%.
The authors have said that their article is being misrepresented, the figures are complimentary not a contradiction"
COVID-19 vaccine efficacy and effectiveness—the elephant (not) in the room
Approximately 96 COVID-19 vaccines are at various stages of clinical development.1 At present, we have the interim results of four studies published in scientific journals (on the Pfizer–BioNTech BNT162b2 mRNA vaccine,2 the Moderna–US National Institutes of Health [NIH] mRNA-1273 vaccine,3 the...
www.thelancet.com
I'm clueless about relative risk reduction and ARR so had to Google the terms and their use relating to vaccines. Tried explaining to the poster though not entirely sure I'm correct. Kept repeating the same thing in different ways but the antiva poster was sticking to their interpretation. Interested to know if the two, of many, replies below are correct.
"They're just saying it's useful but not that it invalidates the RRR percentage. If you have 2 groups of 20,000 people and 200 of the unvaccinated get covid and none of the vaccinated do then the RRR is 100% but the ARR would be 1%. Whatever the ARR is the RRR stays the same. It's looking at a group outcome but the ARR is looking at individual risk. If only 1% of the population are catching covid the benefit, or reduction in risk is low as you're unlikely to catch covid"
"I think you're not getting what absolute risk reduction means. I didn't until I read the article and looked it up.
In the Pfizer trial there were 21,720 people who got two doses of the vaccine, and 21,728 got two doses of placebo. Study was two months long. 8 vaccinated and 162 placebo group tested positive for covid. That means the risk of COVID-19 in the vaccinated group was 8/21,720 = 0.037%, and the risk in the placebo group was 162/21,728 = 0.745%. The ARR is the difference in risk between the two groups. In this case it would be = 0.745% – 0.037% = 0.708%.
The authors have said that their article is being misrepresented, the figures are complimentary not a contradiction"
