I have very little background in Medicine, pardon me for that. I came across this reference recently. Loosely speaking, this study aims at testing the effect of azithromycin and hydroxychloroquin for treatment of COVID-19.

In the reference, they claim to have tested the effectiveness of combination of azithromycin and hydroxychloroquin on COVID-19 patients. They measure the viral load in patients after a few days and determine the effectiveness of the combination using that and they compare it with a no intervention group. My main question is, how important is it to account for something like placebo in this study if a no intervention group is already present? I would guess, if one is using a measure like viral load, the effects of placebo on it should be negligible. Is that correct? From what I know, placebo would play a significant role if their metric of evaluating recovery would be something like measuring the body temperature or relief in throat etc. which are the symptoms of COVID-19.

With the help of my friend, I found this reference(I do not understand the jargon) which claims that, for a bacterial infection, the immune response is causally linked with reward mechanisms which mediate positive expectations that are a part of placebo. Is this result significant enough to affect the consequences of the study on COVID-19(linked above) drastically?

  • You may wish to see if the WHO study Solidarity contains a placebo arm, or, rather an arm with none of the trial drugs. I expect it does. – Graham Chiu Mar 23 '20 at 20:34
  • @GrahamChiu, I guess the study is going to start soon, would be interesting to see that. Wouldn't the presence of arm depend on the choice of measure determine whether the placebo arm is significant or not? I would presume that they will likely measure the viral load. Do you expect to see a placebo arm if the measure is viral load? if yes, why? and is it significant? Also, it seems that the study might not test for the combination of Hydroxychloroquin and Azithromycin, its just Hydroxychloroquin that is being tested[Sciencemag.org article], but I guess it shouldn't matter. – lurker Mar 23 '20 at 20:50
  • There are different reasons for Placebo groups and for Control groups - some of them overlap and others do not. – Bryan Krause Mar 23 '20 at 21:02
  • This trial is very simple so that virtually no data collection is required by the participants who are likely overwhelmed with clinical work. So, testing for viral loads is not a requirement. – Graham Chiu Mar 23 '20 at 21:11
  • Ok, Thanks @GrahamChiu , I need to read about it. – lurker Mar 23 '20 at 21:16

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