Remember late-winter 2020 in this manufactured black swan event, Chinese epidemic researchers reported direct co-morbidity with any previous SARS vaccine -- which China has ("had", more likely) a population of, but only a miniscule population exists in the US -- and then China quickly shut down any further study on that, about the time they had successfully seeded their virus globally (March, 2020) and maxed out their crematoriums, ie, they stopped giving a shit about co-morbidities.
There is at least one famous House of Saud who croaked on COVID almost surely enhanced by their prior MERS vaccination.
SARS-CoV-2 Spike Protein Elicits Cell Signaling in Human Host Cells: Implications for Possible Consequences of COVID-19 Vaccines
https://www.mdpi.com/2076-393X/9/1/36/htm