Still comes back to what was mentioned before though, how do we know these vaccines work if nobody has been infected yet to see what happens?
Also, how long does the protection last?
We shouldn’t preempt, but the process is basically to select the trial participants and then give some of them the real vaccine and others an inert placebo, then then let them go about their lives. Nobody knows which one they got, vaccine or placebo. If the vaccine works, you then expect some of the placebo group to get the virus, but hardly any of the vaccine group to get it.
You also monitor both groups for side effects etc, so that if (say) 90% of the vaccine group get an ingrown toenail, vs 2% of the placebo group, that ingrown toenails might be a side effect.
The problem is that the number of participants and of infected & uninfected need to be large, to be statistically convincing. If just a handful were trialed, and only one of them got the virus, that could obviously be fluke. I believe the Oxford vaccine trials were partly conducted large scale in places like Brazil, where the numbers have been bigger, after it started to quieten down here in the UK.
Hopefully though, today’s publication might end some of the guesswork.