Randomized Control Trials are not the one and only way to prove something.
> Conclusions: Parachute use did not reduce death or major traumatic injury when jumping from aircraft in the first randomized evaluation of this intervention. However, the trial was only able to enroll participants on small stationary aircraft on the ground, suggesting cautious extrapolation to high altitude jumps.
If N95 masks in a virus laden environment are akin to parachutes when falling from an airplane - that's great news. I'm super happy to be educated on this given my unbroken record of never having been indoor in 18+ months without one. Happy to know that it's been making an absolute difference.
> Upgrading face masks to filtering face piece (FFP3) respirators for healthcare workers on covid-19 wards produced a dramatic reduction in hospital acquired SARS-CoV-2 infections, according to research carried out at Addenbrooke’s Hospital in Cambridge.
> Once FFP3 respirators were introduced [as opposed to simple surgical masks], the number of cases attributed to exposure on covid-19 wards dropped dramatically—in fact, our model suggests that FFP3 respirators may have cut ward based infection to zero.
FFP3 is a bit better than N95 (it's equivalent to N99).
N95 masks came from industry, but there were no RCT studies there. People just noted that they obviously worked, through arguably one can easily feel that a saw dust mask works as opposed to one against viruses.
I've done extensive research on this subject, for coronavirus purposes N95 is equivalent to FFP3. The most important aspect is having head bands (as opposed to ear loops) to secure a tight fit. N95 typically have head bands. FFP2/KN95 (filtering equivalent to N95) typically don't, which is why FFP3 are sometimes preferred. There are also regulatory reasons to use FFP3.
3M also manufactures FFP3 masks. Not sure if they sell them outside EU though.
Sure, they're not the only way - but they are definitively the best way, and nothing is stopping this kind of study from happening, especially in low risk (age) groups / populations.
I think it might even be ethical if you could find such a low-risk cohort that was adamantly opposed to the wearing of masks, and under no circumstances whatsoever, except perhaps because they are scientific minded individuals and would like to prove they are not required, would wear them.
Given other beliefs those people are likely to hold, at least here in the US, I suspect there would be some other behaviors they would be systematically more likely to engage in that would act as confounds.
> Conclusions: Parachute use did not reduce death or major traumatic injury when jumping from aircraft in the first randomized evaluation of this intervention. However, the trial was only able to enroll participants on small stationary aircraft on the ground, suggesting cautious extrapolation to high altitude jumps.
https://www.bmj.com/content/363/bmj.k5094