Does it really happen like that? Or is that a theoretical framework? Also who does the study? What are their incentives to be unbiased?
To be frank what you wrote sounds like a fairytale to me. For the reliability of many of the tests that have been used to determine whether or not someone has Covid, I am skeptical of most Covid related data. I don't think we really know how many people have it, what the chances of getting it are, if any of the data is at all being based on PCR testing we might as well be trying to read tea leaves or goat entrails for answers about Covid.
It's not a fairytale.
"In an ongoing multinational, placebo-controlled, observer-blinded, pivotal efficacy trial, we randomly assigned persons 16 years of age or older in a 1:1 ratio to receive two doses, 21 days apart, of either placebo or the BNT162b2 vaccine candidate (30 μg per dose)."
"A total of 43,548 participants underwent randomization, of whom 43,448 received injections: 21,720 with BNT162b2 and 21,728 with placebo. There were 8 cases of Covid-19 with onset at least 7 days after the second dose among participants assigned to receive BNT162b2 and 162 cases among those assigned to placebo; BNT162b2 was 95% effective in preventing Covid-19 (95% credible interval, 90.3 to 97.6). Similar vaccine efficacy (generally 90 to 100%) was observed across subgroups defined by age, sex, race, ethnicity, baseline body-mass index, and the presence of coexisting conditions. Among 10 cases of severe Covid-19 with onset after the first dose, 9 occurred in placebo recipients and 1 in a BNT162b2 recipient. The safety profile of BNT162b2 was characterized by short-term, mild-to-moderate pain at the injection site, fatigue, and headache. The incidence of serious adverse events was low and was similar in the vaccine and placebo groups."
They're measuring actual incidence of illness, not just whether a person receives a positive test result. The incentive not to lie is the risk of multibillion dollar fines to the US government (
https://en.wikipedia.org/wiki/List_of_largest_pharmaceutical_settlements), criminal exposure (since we are talking about fraud), and legal exposure to every government that the vaccine has been licensed to, on the basis of the trial data. On top of the political and PR fallout that would result. The other thing is that there is a second level of falsifiability, since governments should be able to check if people who have received the second dose of the vaccine are still contracting covid-19, and at what rate.