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> Had the clinical trials run in a "less ethical" way, say by taking young and healthy people like myself And what exactly would that have told you about the s

> Had the clinical trials run in a "less ethical" way, say by taking young and healthy people like myself And what exactly would that have told you about the safety and effectiveness of the vaccine for the people at risk, those who are neither young nor healthy? And how many people would you need to challenge to show that the vaccine prevents deaths or even serious disease? The young and healthy rarely get the full brunt of the disease.

ericb 6y ago
You can still measure: the immune response, antibodies, white blood cells, scenarios in which the contagion can spread, minimal social distance needed, length of exposure required for transmission, how much masks stop transmission, safety (risk reduction), and peak efficacy. You can do it on a much shorter timescale, and with fewer lives lost. What if we had needed to iterate to fix problems in the vaccine? How many would die waiting? To your specific question, you still derisk it for the elderly. If it causes problems in young adults, you quit because it would probably cause even more problems in riskier groups. If it doesn't, you move forward into older groups. Let's not pretend you would learn nothing that would speed things along. Some of these questions aren't answered quantitatively even now.
- oldgradstudent 6y ago
  > You can still measure: the immune response, antibodies, white blood cells, scenarios in which the contagion can spread, minimal social distance needed, length of exposure required for transmission, how much masks stop transmission, safety (risk reduction), and peak efficacy. [...] Of course. These are all great uses for challenge studies, I was responding specifically to testing the vaccine using a challenge study on healthy young adults. > If it causes problems in young adults, you quit because it would probably cause even more problems in riskier groups. If it doesn't, you move forward into older groups. It turns out that both Pfizer and Moderna trials have shown much more adverse reactions in the young than the old. Testing on the wrong population may result in rejecting a vaccine that could be perfectly safe on the at-risk population, but inappropriate for the general population. > Let's not pretend you would learn nothing that would speed things along Of course not. You could learn a lot, just not about the safety and efficacy profile of the vaccine on the at-risk population.
mjmahone17 6y ago
> And what exactly would that have told you about the safety and effectiveness of the vaccine for the people at risk, those who are neither young nor healthy? So if the goal was to reduce transmission, you can save a lot of lives of those at risk by vaccinating the young and healthy. It would be reasonable to basically use challenge studies to get a lower transmission rate, while in parallel using standard trials to prove the efficacy in at risk populations. Getting more data quicker is usually a good way to make more informed decisions, even if the data isn’t exactly what you want it to be to make the perfectly optimal choices.
- runako 6y ago
  > So if the goal was to reduce transmission, you can save a lot of lives of those at risk by vaccinating the young and healthy. Has this been tested yet? Is there evidence that this is true beyond the broad population surveys like those from Israel? (The accuracy of those data were hotly debated here last week.) Surely a study to determine actual transmission rates would be much more complex than one to determine whether young & healthy people are infected after inoculation (which again: not that useful of a data point by itself)?
  - Closi 6y ago
    Well transmission effectiveness is a good example of something that’s much easier to measure in a controlled challenge study and almost impossible to measure pre-rollout without it!
    - runako 6y ago
      How? The vaccinated individuals would come into contact with lots of people who are not vaccinated. How do you track all of them to determine if vaccinated individuals can transmit the disease? That seems like a much larger logistical problem that differs from the existing (and challenge) trials in very material ways.
      - Closi 6y ago
maxerickson 6y ago
Administering a vaccine that is only effective in young healthy people to young healthy people makes everyone safer. And that's the bad outcome where the slower trials in more at risk people don't work out. In the good outcome, when you decide it is safe and effective in vulnerable people, production and administration have already been scaled out. (could study viral load in a challenge trial where you don't have to test thousands of uninfected people to find asymptomatic cases…)
this_user 6y ago
The important thing is that these trials can only be performed on the young and healthy who are at the least risk of severe illness and death. This means any results gained from these would have been essentially worthless when it comes to the patients most at risk. Consequently, one would have still had to run the regular P3 trials with a diverse group of subjects. Therefore, any acceleration in the vaccine's development process would have at best been marginal. This is also what the industry association of German drug manufacturers has pointed out in a statement, dismissing the British challenge trials as ethically dubious and effectively useless.

ericb 6y ago

You can still measure: the immune response, antibodies, white blood cells, scenarios in which the contagion can spread, minimal social distance needed, length of exposure required for transmission, how much masks stop transmission, safety (risk reduction), and peak efficacy. You can do it on a much shorter timescale, and with fewer lives lost. What if we had needed to iterate to fix problems in the vaccine? How many would die waiting? To your specific question, you still derisk it for the elderly. If it causes problems in young adults, you quit because it would probably cause even more problems in riskier groups. If it doesn't, you move forward into older groups. Let's not pretend you would learn nothing that would speed things along. Some of these questions aren't answered quantitatively even now.

oldgradstudent 6y ago
> You can still measure: the immune response, antibodies, white blood cells, scenarios in which the contagion can spread, minimal social distance needed, length of exposure required for transmission, how much masks stop transmission, safety (risk reduction), and peak efficacy. [...] Of course. These are all great uses for challenge studies, I was responding specifically to testing the vaccine using a challenge study on healthy young adults. > If it causes problems in young adults, you quit because it would probably cause even more problems in riskier groups. If it doesn't, you move forward into older groups. It turns out that both Pfizer and Moderna trials have shown much more adverse reactions in the young than the old. Testing on the wrong population may result in rejecting a vaccine that could be perfectly safe on the at-risk population, but inappropriate for the general population. > Let's not pretend you would learn nothing that would speed things along Of course not. You could learn a lot, just not about the safety and efficacy profile of the vaccine on the at-risk population.

mjmahone17 6y ago

> And what exactly would that have told you about the safety and effectiveness of the vaccine for the people at risk, those who are neither young nor healthy? So if the goal was to reduce transmission, you can save a lot of lives of those at risk by vaccinating the young and healthy. It would be reasonable to basically use challenge studies to get a lower transmission rate, while in parallel using standard trials to prove the efficacy in at risk populations. Getting more data quicker is usually a good way to make more informed decisions, even if the data isn’t exactly what you want it to be to make the perfectly optimal choices.

runako 6y ago
> So if the goal was to reduce transmission, you can save a lot of lives of those at risk by vaccinating the young and healthy. Has this been tested yet? Is there evidence that this is true beyond the broad population surveys like those from Israel? (The accuracy of those data were hotly debated here last week.) Surely a study to determine actual transmission rates would be much more complex than one to determine whether young & healthy people are infected after inoculation (which again: not that useful of a data point by itself)?
- Closi 6y ago
  Well transmission effectiveness is a good example of something that’s much easier to measure in a controlled challenge study and almost impossible to measure pre-rollout without it!
  - runako 6y ago
    How? The vaccinated individuals would come into contact with lots of people who are not vaccinated. How do you track all of them to determine if vaccinated individuals can transmit the disease? That seems like a much larger logistical problem that differs from the existing (and challenge) trials in very material ways.
    - Closi 6y ago

maxerickson 6y ago

Administering a vaccine that is only effective in young healthy people to young healthy people makes everyone safer. And that's the bad outcome where the slower trials in more at risk people don't work out. In the good outcome, when you decide it is safe and effective in vulnerable people, production and administration have already been scaled out. (could study viral load in a challenge trial where you don't have to test thousands of uninfected people to find asymptomatic cases…)

this_user 6y ago

The important thing is that these trials can only be performed on the young and healthy who are at the least risk of severe illness and death. This means any results gained from these would have been essentially worthless when it comes to the patients most at risk. Consequently, one would have still had to run the regular P3 trials with a diverse group of subjects. Therefore, any acceleration in the vaccine's development process would have at best been marginal. This is also what the industry association of German drug manufacturers has pointed out in a statement, dismissing the British challenge trials as ethically dubious and effectively useless.