The initial clinical trials were done in such a way. I have my own qualms with their outcomes myself. In fact, the phase III Moderna clinical trial was the reason I chose NOT to get vaccinated. Their study discussion did NOT mention why their control group contracted COVID at twice the rate of the general population during the same time period. There are many logical explanations, for instance those with placebo may have engaged in more risky behavior due to belief they were immune. It could have been natural variability due to random selection itself had coincidental regional bias. Many things, but they chose not to discuss it which meant that they hoped nobody else noticed. That study was later altered to withhold data that one could use to retroactively derive the bias. That, however, doesn't debunk actual real-world retrospective data. Other studies are retrospective and indicative of real world application and the cards fall where they may. Lack of "control" in real-world retrospective studies in now way invalidates findings. In fact, clinical trials seek to predict real world application. So much so that a systematic review and retrospective meta-analysis is the best way to give a report card of efficacy of medical intervention.