You can test safety glasses in a lab without putting anyone at risk of anything. Put them in a fixture and throw things at them first, then put them on a simulated human head and throw more things at them. You can keep at this until you are pretty sure that the new safety glasses are at least roughly as good as the old ones before you put them out to market.
But the only "lab" we have for testing vaccines is human bodies. Fortunately, we are talking about the flu and not deadly super-ebola.
I can no longer tell whether you're advocating for a test of the new vaccine against a placebo, or of not testing the new vaccine at all. The risk to study participants of using their bodies as the "lab" for testing the vaccine has nothing to do with whether other trial participants receive a placebo. That risk is controlled by doing stage 1/2 trials at small scale to confirm safety before you move on to a stage 3 trial (subject of this article) at a wider scale to measure efficacy.
I bet that you could get plenty of volunteers willing to take the informed risk of having a 50/50 chance at getting either the new flu shot or a placebo. Some people are at high risk from the flu and would want the (supposedly) proven shot.
I bet that you could get plenty of volunteers willing to take the informed risk of having a 50/50 chance at getting either the new flu shot or a placebo. Some people are at high risk from the flu and would want the (supposedly) proven shot.
But roughly half of all adults in America feel no particular danger from the flu, as we know because they don't get the shot now. It would only take a few thousand people from that group of ~100 million to establish a proper baseline. Unless the new shot literally has negative efficacy, they are at no more risk for participating than they had already accepted.
I think you're basically describing the natural experiment we run on already-approved vaccines every flu season. Some people get the shot, some people choose not to, and health agencies measure the proportion of each population that end up with the flu.
That's certainly an informative exercise, but I don't see what value it would add to simulate that experiment as a part of the new vaccine approval process, even if we disregard or solve the ethical question. If the natural experiment shows that established vaccines are more effective than being unvaccinated, and the stage 3 trial shows that the new vaccine is more effective than the established vaccines, what are we missing?