5 ms·

Can someone explain to me why double blind is necessary or useful for a vaccine trial such as this? It seems obvious to me on something like a pain medicine, bu

by cwhiz 6y ago

Can someone explain to me why double blind is necessary or useful for a vaccine trial such as this? It seems obvious to me on something like a pain medicine, but on a vaccine it seem a pointless. Is placebo an actual issue with a vaccine? It honestly seems borderline unethical to give people a placebo vaccine.

keyme 6y ago
Placebo can have an effect on side effects.
- cwhiz 6y ago
  Are they testing for side effects in all three stages? I thought the first two trials were for safety and the third was for efficacy. Is that incorrect?
  - tcoff91 6y ago
    They're absolutely monitoring side effects during phase 3. some safety effects can be rare enough that they don't show up in phase 1/2.
    - cwhiz 6y ago
      Okay. I’m still having a hard time understanding how placebo helps them test for side effects.
      - Izkata 6y ago
        I imagine: If a given side-effect occurs at the same rate in both groups, it's unlikely to be caused by the vaccine and is more likely to be psychosomatic.
        chrisrogers 6y ago
        Psychosomatic, or the result of administering an IV shot, or environmental.
  - ksk 6y ago
    Data on adverse reactions is captured by the CDC/FDA/HHS throughout the lifecycle of the vaccine, from all the phases of clinical trials to its use in the general population. Its required by law.
koboll 6y ago
You're right, and researchers are aware of this: https://www.statnews.com/2020/09/03/placebos-arent-needed-challenge-trials-covid-19-vaccines/ https://www.statnews.com/2020/09/03/placebos-arent-needed-ch... Also, there is a very strong risk, given the global situation, that the longer placebo-controlled trials go on, the less reliable the data will be, because control-group subjects will ignore the rules of the study and go get vaccinated as soon as it's broadly available just in case. So even just looking at data quality and excluding other considerations, placebos have major risks that probably outweigh the benefits of administering them for months or years like a usual vaccine trial would.
DiogenesKynikos 6y ago
People who know they've been vaccinated will behave more recklessly than people who haven't been vaccinated. You need to have a control group, in order to assess the efficacy (and safety) of the vaccine. If the control group is wearing masks and socially distancing, but the vaccinated group is going partying at bars and clubs every night, then comparisons of how often each group gets infected won't have much meaning. It's only unethical to withhold the vaccine if you know that it's safe and effective. The whole point of the study is to figure out if that's the case. It's possible for vaccine candidates to be ineffective, or even harmful (e.g., antibody-dependent enhancement).
- cwhiz 6y ago
  What you’re describing as “reckless behavior” is just normal behavior in a non-covid world. If vaccine candidates are social distancing, wearing masks, and staying home how will the researchers get the data they need? If you are following “covid best practices” it is extremely unlikely that you will contract covid. Would the researchers not want people to go out and live their normal lives?
  - jberryman 6y ago
    The point is if the two groups behave differently wrt risk then the trial is probably ruined. Maybe you're assuming the vaccine will be 100% effective; experts I've heard are saying to expect something like the flu shot.
    - bluGill 6y ago
      Experts need to control to control expections. The flu shot like 50% effenceny is a possibility, and we know anti vaxxers latch onto that with confused statistics. The flu shot is poorly effective because the flu mutates though, covid is more stable so odds are that the vaccine will be more effective, but we are still playing odds of something we don't know, so it is best to assume the worse.
      - DiogenesKynikos 6y ago
deleted 6y ago
[deleted]
tgsovlerkhgsel 6y ago
If you tell people whether they're now vaccinated, they're going to take a lot more risks. You may still have increased risk taking behavior if you don't tell them whether they got the real vaccine or placebo, but it will be equally increased across the experiment and control groups.
- raverbashing 6y ago
  And? Having them expose themselves more to the virus is a "good thing" (though tell them how long should they wait for the immunity to set in) Yes, with the control group you would have a base for how many people you would have expected to be infected, so there's that, but you "could" get that from other observations
  - whimsicalism 6y ago
    > you "could" get that from other observations No, if they change their behavior, you couldn't. Why are so many people commenting when they clearly don't understand knowledge-creation/statistics/methodology?
    - harry8 6y ago
      >Why are so many people commenting when they clearly don't understand knowledge-creation/statistics/methodology? Because (a) we want to understand. and (b) reasonable experts differ on what constitutes proper methodology which is constantly being improved. Surely the effect size of a useful vaccine is large enough that modified behaviour of the vaccinated does not matter at all. We're not looking for a small incremental improvement in contraction rate of the virus here, we're looking for a very large percentage of those who have been administered the vaccine not getting covid. Yeah it could change behaviour but so what? How is that going to bias the result to suggest it isn't working if it is? (or vice-versa)
    - raverbashing 6y ago
      > Why are so many people commenting when they clearly don't understand knowledge-creation/statistics/methodology? You talk about knowledge-creation and answer with a dogmatic tautology. Then people wonder why anti-scientific sentiment is at high levels...
bausano_michael 6y ago
You might like Greg Egan's short story "Blood sisters" which addresses exactly this topic. It's one of the short stories in the book "Axiomatic".
nshepperd 6y ago
To add to the other comments: because giving a placebo is essential for the experimental results to have any validity, not giving a placebo would be imo way more unethical, since it would mean you are exposing people to a medical risk (experimental vaccine) for no scientific benefit. (Needless to say, running an invalid vaccine trial also has very bad consequences: it would delay the actual deployment of a working vaccine to the general public, resulting in millions of unnecessary person-hours of potential virus exposure.)

by cwhiz 6y ago

keyme 6y ago

Placebo can have an effect on side effects.

cwhiz 6y ago
Are they testing for side effects in all three stages? I thought the first two trials were for safety and the third was for efficacy. Is that incorrect?
- tcoff91 6y ago
  They're absolutely monitoring side effects during phase 3. some safety effects can be rare enough that they don't show up in phase 1/2.
  - cwhiz 6y ago
    Okay. I’m still having a hard time understanding how placebo helps them test for side effects.
    - Izkata 6y ago
      I imagine: If a given side-effect occurs at the same rate in both groups, it's unlikely to be caused by the vaccine and is more likely to be psychosomatic.
      - chrisrogers 6y ago
        Psychosomatic, or the result of administering an IV shot, or environmental.
- ksk 6y ago
  Data on adverse reactions is captured by the CDC/FDA/HHS throughout the lifecycle of the vaccine, from all the phases of clinical trials to its use in the general population. Its required by law.

koboll 6y ago

You're right, and researchers are aware of this: https://www.statnews.com/2020/09/03/placebos-arent-needed-challenge-trials-covid-19-vaccines/ https://www.statnews.com/2020/09/03/placebos-arent-needed-ch... Also, there is a very strong risk, given the global situation, that the longer placebo-controlled trials go on, the less reliable the data will be, because control-group subjects will ignore the rules of the study and go get vaccinated as soon as it's broadly available just in case. So even just looking at data quality and excluding other considerations, placebos have major risks that probably outweigh the benefits of administering them for months or years like a usual vaccine trial would.

DiogenesKynikos 6y ago

People who know they've been vaccinated will behave more recklessly than people who haven't been vaccinated. You need to have a control group, in order to assess the efficacy (and safety) of the vaccine. If the control group is wearing masks and socially distancing, but the vaccinated group is going partying at bars and clubs every night, then comparisons of how often each group gets infected won't have much meaning. It's only unethical to withhold the vaccine if you know that it's safe and effective. The whole point of the study is to figure out if that's the case. It's possible for vaccine candidates to be ineffective, or even harmful (e.g., antibody-dependent enhancement).

cwhiz 6y ago
What you’re describing as “reckless behavior” is just normal behavior in a non-covid world. If vaccine candidates are social distancing, wearing masks, and staying home how will the researchers get the data they need? If you are following “covid best practices” it is extremely unlikely that you will contract covid. Would the researchers not want people to go out and live their normal lives?
- jberryman 6y ago
  The point is if the two groups behave differently wrt risk then the trial is probably ruined. Maybe you're assuming the vaccine will be 100% effective; experts I've heard are saying to expect something like the flu shot.
  - bluGill 6y ago
    Experts need to control to control expections. The flu shot like 50% effenceny is a possibility, and we know anti vaxxers latch onto that with confused statistics. The flu shot is poorly effective because the flu mutates though, covid is more stable so odds are that the vaccine will be more effective, but we are still playing odds of something we don't know, so it is best to assume the worse.
    - DiogenesKynikos 6y ago

deleted 6y ago

[deleted]

tgsovlerkhgsel 6y ago

If you tell people whether they're now vaccinated, they're going to take a lot more risks. You may still have increased risk taking behavior if you don't tell them whether they got the real vaccine or placebo, but it will be equally increased across the experiment and control groups.

raverbashing 6y ago
And? Having them expose themselves more to the virus is a "good thing" (though tell them how long should they wait for the immunity to set in) Yes, with the control group you would have a base for how many people you would have expected to be infected, so there's that, but you "could" get that from other observations
- whimsicalism 6y ago
  > you "could" get that from other observations No, if they change their behavior, you couldn't. Why are so many people commenting when they clearly don't understand knowledge-creation/statistics/methodology?
  - harry8 6y ago
    >Why are so many people commenting when they clearly don't understand knowledge-creation/statistics/methodology? Because (a) we want to understand. and (b) reasonable experts differ on what constitutes proper methodology which is constantly being improved. Surely the effect size of a useful vaccine is large enough that modified behaviour of the vaccinated does not matter at all. We're not looking for a small incremental improvement in contraction rate of the virus here, we're looking for a very large percentage of those who have been administered the vaccine not getting covid. Yeah it could change behaviour but so what? How is that going to bias the result to suggest it isn't working if it is? (or vice-versa)
  - raverbashing 6y ago
    > Why are so many people commenting when they clearly don't understand knowledge-creation/statistics/methodology? You talk about knowledge-creation and answer with a dogmatic tautology. Then people wonder why anti-scientific sentiment is at high levels...

bausano_michael 6y ago

You might like Greg Egan's short story "Blood sisters" which addresses exactly this topic. It's one of the short stories in the book "Axiomatic".

nshepperd 6y ago

To add to the other comments: because giving a placebo is essential for the experimental results to have any validity, not giving a placebo would be imo way more unethical, since it would mean you are exposing people to a medical risk (experimental vaccine) for no scientific benefit. (Needless to say, running an invalid vaccine trial also has very bad consequences: it would delay the actual deployment of a working vaccine to the general public, resulting in millions of unnecessary person-hours of potential virus exposure.)