7 ms·

What exactly does "percent protection" mean in these announcements? Can we use the definition to derive a percent protection associated with having been throug

What exactly does "percent protection" mean in these announcements? Can we use the definition to derive a percent protection associated with having been through the virus? Is there a percent protection associated with your age / gender / race profile? It feels like the number doesn't mean much without having a similar number for the null cases.

lbeltrame 6y ago
It is a reduction of the risk of symptomatic disease by 76% once vaccinated. But more importantly, there were no hospitalizations or deaths in the vaccinated people. This is a point the media often overlooks.
- nmca 6y ago
  Because the "no hospitalisations or deaths" claim from the first Oxford paper was comparing n=2 to n=0 and thus was miles from significance. If the new paper has updated data on this happy to be corrected.
  - disgruntledphd2 6y ago
    Tbh, the reductions in hospitalisations has been super high for almost all the vaccines, which is great news.
  - lbeltrame 6y ago
    It is a constant in any vaccine, including the "lowest" performers from Sinovac and Sinopharm. At this point, I'm inclined to believe that any resonably effective vaccine will have this effect.
- adamc 6y ago
  It's huge. On the whole, avoiding hospitalizations is far more important than whether people had mild cases.
  - renaudg 6y ago
    Not quite when it comes to stopping the epidemic, because transmission seems to be highly correlated to viral load and thus to severity as well.
- orra 6y ago
  Indeed. These are some of the best vaccines ever invented[1]. Look at the two charts[2] in this paper from the UK's JCVI. They show the number of severe incidents (severe COVID or death). The linear or exponential growth curves are for people on the placebos. The almost flat lines are for people on the Pfizer-BioNTech and the Oxford-AstraZeneca vaccines, respectively. Oh, after just the initial dose, not the booster! [1] https://www.nytimes.com/2021/01/18/briefing/donald-trump-pardon-phil-spector-coronavirus-deaths.html https://www.nytimes.com/2021/01/18/briefing/donald-trump-par... [2] https://www.cas.mhra.gov.uk/ViewandAcknowledgment/ViewAttachment.aspx?Attachment_id=103741 https://www.cas.mhra.gov.uk/ViewandAcknowledgment/ViewAttach...
- harry8 6y ago
  Is it known what the effect is on so-called "long covid" and other pretty serious long-term covid affects that might be suffered by people who don't get it badly enough to go to hospital?
  - o-__-o 6y ago
    Anecdotal evidence I’ve been gathering points to the vaccine making long term covid go away. I have no idea how this works, but it is tempting me into signing up for the vaccine
    - harry8 6y ago
      That's the dream. It would be nice to have something better than anecdotal evidence. I hope we do. I wonder why the evidence of lack of it isn't being publicised.
    - iainmerrick 6y ago
      Out of curiosity, why would you not want to sign up? All the vaccine results have been amazingly positive.
      - lixtra 6y ago
        What’s the probability that today’s scientists look as ridiculous in a few decades as the ones from a few decades ago look like today? Asbestos was considered a great building material. While science had improved in absolute terms, there is a chance to screw up in new ways.
        iainmerrick 6y ago
        Sounds like you’re not concerned about all scientific advances, you just want to give them enough to time to be sure there are no adverse side-effects. Vaccines have been around for a very long time and have proven to be incredibly effective and safe. Nobody is embarrassed about how the vaccines for smallpox, polio and measles have worked out (apart from some misinformation in recent years -- you’ll have to do your own research on that one. If you come to it with an open mind I think you’ll come to agree those vaccines are safe.)
lawl 6y ago
Afaik it means that if you have a control group that isn't vaccinated vs this group (both should be drawn randomly of course), you will see 76% less infections in this group.
- reportingsjr 6y ago
  That is not what any of the vaccine studies have said so far. I haven't read this one, but I bet it also doesn't say this. The stated efficacy/protection percentages that have been presented so far have been for the reduction of _symptoms_. There haven't been any studies on vaccines preventing infections, probably due to lack of resources for testing everyone in a trial multiple times.
  - lawl 6y ago
    Maybe i misunderstood OPs question but i don't think that changes much. It's the difference between $measurement between the control group and the test group. If that's the reduction of symptoms here, ok.
    - firethief 6y ago
      We don't know how much it changes. We don't have much information on the difference between the ratio of $measurement0 : $measurement1 between the two groups. Once everyone is vaccinated (antivaxxers don't count, they get what they get), symptom rate is all that matters. But in the interim months, transmission rate from vaccinated sources is incredibly important, which is partly determined by infection rate among vaccinated.
  - Eric_WVGG 6y ago
    IANAD but I'm nearly positive you're incorrect. I spent last night puzzling over what "efficacy" means vis a vis this video: https://www.technologynetworks.com/immunology/videos/covid-19-vaccine-efficacy-explained-its-not-what-you-think-342956 https://www.technologynetworks.com/immunology/videos/covid-1... The author explains that the efficacy number is derived from the the number of the number of people in the control/placebo group infected divided by the total number of infections in the study. 76% efficacy means that, for a given population of people who contracted a disease (ignoring all uninfected), 24% were vaccinated (vaccine failures), 76% were not vaccinated. It has nothing to do with reduction of symptoms. I think this is unintuitive because the "real" solution that laypersons want is, what percentage of vaccinated people exposed to a disease get infected? We can't measure that directly because we can't just expose a bunch of folks to Covid and hope for the best. But if the sample of placebo and vaccinated people is truly random, this would appear to arrive at the same ratio. (re: when I said "ignoring all uninfected"? in a good sample, the ratio of unexposed vaccinated and control units should be about the same)
aqme28 6y ago
Protection of antibodies from a previous infection is somewhere above 90%. https://www.medrxiv.org/content/10.1101/2021.01.15.21249731v1 https://www.medrxiv.org/content/10.1101/2021.01.15.21249731v...

lbeltrame 6y ago

It is a reduction of the risk of symptomatic disease by 76% once vaccinated. But more importantly, there were no hospitalizations or deaths in the vaccinated people. This is a point the media often overlooks.

nmca 6y ago
Because the "no hospitalisations or deaths" claim from the first Oxford paper was comparing n=2 to n=0 and thus was miles from significance. If the new paper has updated data on this happy to be corrected.
- disgruntledphd2 6y ago
  Tbh, the reductions in hospitalisations has been super high for almost all the vaccines, which is great news.
- lbeltrame 6y ago
  It is a constant in any vaccine, including the "lowest" performers from Sinovac and Sinopharm. At this point, I'm inclined to believe that any resonably effective vaccine will have this effect.
adamc 6y ago
It's huge. On the whole, avoiding hospitalizations is far more important than whether people had mild cases.
- renaudg 6y ago
  Not quite when it comes to stopping the epidemic, because transmission seems to be highly correlated to viral load and thus to severity as well.
orra 6y ago
Indeed. These are some of the best vaccines ever invented[1]. Look at the two charts[2] in this paper from the UK's JCVI. They show the number of severe incidents (severe COVID or death). The linear or exponential growth curves are for people on the placebos. The almost flat lines are for people on the Pfizer-BioNTech and the Oxford-AstraZeneca vaccines, respectively. Oh, after just the initial dose, not the booster! [1] https://www.nytimes.com/2021/01/18/briefing/donald-trump-pardon-phil-spector-coronavirus-deaths.html https://www.nytimes.com/2021/01/18/briefing/donald-trump-par... [2] https://www.cas.mhra.gov.uk/ViewandAcknowledgment/ViewAttachment.aspx?Attachment_id=103741 https://www.cas.mhra.gov.uk/ViewandAcknowledgment/ViewAttach...
harry8 6y ago
Is it known what the effect is on so-called "long covid" and other pretty serious long-term covid affects that might be suffered by people who don't get it badly enough to go to hospital?
- o-__-o 6y ago
  Anecdotal evidence I’ve been gathering points to the vaccine making long term covid go away. I have no idea how this works, but it is tempting me into signing up for the vaccine
  - harry8 6y ago
    That's the dream. It would be nice to have something better than anecdotal evidence. I hope we do. I wonder why the evidence of lack of it isn't being publicised.
  - iainmerrick 6y ago
    Out of curiosity, why would you not want to sign up? All the vaccine results have been amazingly positive.
    - lixtra 6y ago
      What’s the probability that today’s scientists look as ridiculous in a few decades as the ones from a few decades ago look like today? Asbestos was considered a great building material. While science had improved in absolute terms, there is a chance to screw up in new ways.
      - iainmerrick 6y ago
        Sounds like you’re not concerned about all scientific advances, you just want to give them enough to time to be sure there are no adverse side-effects. Vaccines have been around for a very long time and have proven to be incredibly effective and safe. Nobody is embarrassed about how the vaccines for smallpox, polio and measles have worked out (apart from some misinformation in recent years -- you’ll have to do your own research on that one. If you come to it with an open mind I think you’ll come to agree those vaccines are safe.)

lawl 6y ago

Afaik it means that if you have a control group that isn't vaccinated vs this group (both should be drawn randomly of course), you will see 76% less infections in this group.

reportingsjr 6y ago
That is not what any of the vaccine studies have said so far. I haven't read this one, but I bet it also doesn't say this. The stated efficacy/protection percentages that have been presented so far have been for the reduction of _symptoms_. There haven't been any studies on vaccines preventing infections, probably due to lack of resources for testing everyone in a trial multiple times.
- lawl 6y ago
  Maybe i misunderstood OPs question but i don't think that changes much. It's the difference between $measurement between the control group and the test group. If that's the reduction of symptoms here, ok.
  - firethief 6y ago
    We don't know how much it changes. We don't have much information on the difference between the ratio of $measurement0 : $measurement1 between the two groups. Once everyone is vaccinated (antivaxxers don't count, they get what they get), symptom rate is all that matters. But in the interim months, transmission rate from vaccinated sources is incredibly important, which is partly determined by infection rate among vaccinated.
- Eric_WVGG 6y ago
  IANAD but I'm nearly positive you're incorrect. I spent last night puzzling over what "efficacy" means vis a vis this video: https://www.technologynetworks.com/immunology/videos/covid-19-vaccine-efficacy-explained-its-not-what-you-think-342956 https://www.technologynetworks.com/immunology/videos/covid-1... The author explains that the efficacy number is derived from the the number of the number of people in the control/placebo group infected divided by the total number of infections in the study. 76% efficacy means that, for a given population of people who contracted a disease (ignoring all uninfected), 24% were vaccinated (vaccine failures), 76% were not vaccinated. It has nothing to do with reduction of symptoms. I think this is unintuitive because the "real" solution that laypersons want is, what percentage of vaccinated people exposed to a disease get infected? We can't measure that directly because we can't just expose a bunch of folks to Covid and hope for the best. But if the sample of placebo and vaccinated people is truly random, this would appear to arrive at the same ratio. (re: when I said "ignoring all uninfected"? in a good sample, the ratio of unexposed vaccinated and control units should be about the same)

aqme28 6y ago

Protection of antibodies from a previous infection is somewhere above 90%. https://www.medrxiv.org/content/10.1101/2021.01.15.21249731v1 https://www.medrxiv.org/content/10.1101/2021.01.15.21249731v...