[chrisrogers]

It's rudimentary to figure out if you got a vaccine or placebo. Live vaccines tend to produce the type of temporary localized soreness you experience with a flue shot. Placebos do not.

Really it's about measuring how likely vaccinated participants are to contracting the virus than those that received the placebo.

[GuB-42]

The placebo is the meningitis vaccine.

A real vaccine, with side effects that are similar to what is expected of the covid-19 vaccine. It is a well tested and safe vaccine and it will protect you from meningitis but not from covid-19.

They are doing that exactly for the reason you are mentioning. Of course, participants are aware of the nature of the placebo they might receive.

[samoa42]

> The placebo is the meningitis vaccine

wtf?! a placebo should by definition have no effect at all

[GuB-42]

A placebo doesn't have therapeutic value but it doesn't mean it has no effect at all. And the Meningitis vaccine doesn't have therapeutic value in the contest of Covid-19.

In fact, there are even placebo surgeries. They put you to sleep, cut you open, and stitch you back without actually doing anything inside your body. It is far from nothing, the anesthesia and the incision are real. It is important because you want to compare the effect of the actual operation to everything else that is involved in a surgical procedure.

[bbojan]

I think a part (or all) of the placebo group get a different vaccine (e.g. chickenpox), so they still get a reaction.