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35

People could develop antibodies from natural exposure to the virus. The vaccine is trying to cause antibodies to exist in more people (and/or more strongly) than would express them naturally, therefore a good comparison group is a sample taken randomly in the same way as those getting the vaccine: a placebo group. At the same time, these trials tend to ...


13

People in the control group will behave differently if they know they're in the control group. For example, it's not unreasonable to expect people will do less social distancing once they're vaccinated. This will increase their chances of being exposed to the virus.


11

Good question. A phase I trial normally has small numbers, is purely sized to test safety, and it would have no placebo arm. With side effects and antibodies are end points, and a placebo group, this would more often be called a combined phase I/II trial. The purpose of the placebo should be to compare the proportion of side effects and antibodies in the ...


5

This actually has been the subject of a recent debate/article in Nature. The answer is that the approach varies, depending on the perceived risk for the subjects... One method previously used is to create a 3rd arm for participants on the placebo that receive[d] the actual vaccine later. Once a vaccine is granted emergency approval, there is pressure on ...


3

I'll point out some possible situations; these are certainly not exhaustive and some can overlap, but will probably give you a better idea. Some of the terminology I'll use might be a bit US-centric, but the general principles also apply elsewhere. Phase 1 clinical trials Phase 1 trials are the first of four phases that make up a typical clinical trial ...


3

Antibodies only reflect one part of the immune response: the humoral immunity. There is another part of the immunity that can't be detected by dosing the antibodies: the cell-mediated immunity. It produces no antibodies. It only creates effector T-cells that can detect the presence of viruses (or some intra-cellular bacteria) inside body cells and destroy ...


1

The entire point of having a placebo control from a statistics perspective is that the only thing different between the groups is the treatment. You cannot say this is true if you also tell people which group they are in: if you do this, there are now two differences between groups, 1) Treatment vs placebo, 2) Knowing they are in the placebo group vs. ...


1

The National Research Council has explained that: “Precision Medicine refers to the tailoring of medical treatment to the individual characteristics of each patient. It does not literally mean the creation of drugs or medical devices that are unique to a patient, but rather the ability to classify individuals into subpopulations that differ in their ...


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