4 ms·

This hasn't been peer-reviewed yet, but preliminary studies are showing that the vaccines actually do have negative efficacy after 90 days: https://www.medrxiv

by maxk42 5y ago

This hasn't been peer-reviewed yet, but preliminary studies are showing that the vaccines actually do have negative efficacy after 90 days: https://www.medrxiv.org/content/10.1101/2021.12.20.21267966v2 https://www.medrxiv.org/content/10.1101/2021.12.20.21267966v... Yet another point in favor of "Let's not presume until the studies have been completed."

fabian2k 5y ago
> The negative estimates in the final period arguably suggest different behaviour and/or exposure patterns in the vaccinated and unvaccinated cohorts causing underestimation of the VE. This was likely the result of Omicron spreading rapidly initially through single (super-spreading) events causing many infections among young, vaccinated individuals. That's from the linked paper. The authors don't claim at all that the vaccine has negative efficacy, and the study is simply not set up to measure that anyway. You cannot draw this conclusion from the data in this paper.
- maxk42 5y ago
  The study indeed did not set out to prove negative efficacy but a negative VE of 75% is a result that absolutely warrants further research.
- disgruntledphd2 5y ago
  Assuming that Denmark vaccinated oldest/most vulnerable first, this could be a confounded estimate (because age both means you got the vaccine first, and that your immune system will be less effective against Covid). Personally, I think it's a statistical fluke, and was going to argue that it must be due to a smaller sample size until I saw the width of the confidence intervals (CI's get narrower as observations increase). Very odd, and I'll be surprised if that makes it through peer review intact.
  - incrudible 5y ago
    It's a statistical fluke that has been observed with Delta as well, particularly with the AstraZeneca vaccine: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3949410 https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3949410 It stands to reason that the unvaccinated at this point are in large parts hermits who are "protected" by their lifestyle. However, it's also plausible that the non-neutralizing antibodies from the vaccine induce a suboptimal immune response with Omikron.

by maxk42 5y ago

fabian2k 5y ago

> The negative estimates in the final period arguably suggest different behaviour and/or exposure patterns in the vaccinated and unvaccinated cohorts causing underestimation of the VE. This was likely the result of Omicron spreading rapidly initially through single (super-spreading) events causing many infections among young, vaccinated individuals. That's from the linked paper. The authors don't claim at all that the vaccine has negative efficacy, and the study is simply not set up to measure that anyway. You cannot draw this conclusion from the data in this paper.

maxk42 5y ago
The study indeed did not set out to prove negative efficacy but a negative VE of 75% is a result that absolutely warrants further research.
disgruntledphd2 5y ago
Assuming that Denmark vaccinated oldest/most vulnerable first, this could be a confounded estimate (because age both means you got the vaccine first, and that your immune system will be less effective against Covid). Personally, I think it's a statistical fluke, and was going to argue that it must be due to a smaller sample size until I saw the width of the confidence intervals (CI's get narrower as observations increase). Very odd, and I'll be surprised if that makes it through peer review intact.
- incrudible 5y ago
  It's a statistical fluke that has been observed with Delta as well, particularly with the AstraZeneca vaccine: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3949410 https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3949410 It stands to reason that the unvaccinated at this point are in large parts hermits who are "protected" by their lifestyle. However, it's also plausible that the non-neutralizing antibodies from the vaccine induce a suboptimal immune response with Omikron.