There are many possible causes of cancer, just as there are many possible causes of heart inflammation. It's easier in this case as there are fewer variables th

There are many possible causes of cancer, just as there are many possible causes of heart inflammation. It's easier in this case as there are fewer variables than for cancer, and more data on exposure to the various potential factors. Still a total minefield though, in terms of confounding variables. We know for sure which people got the vaccine, but we don't know exactly who got the virus (and, possibly importantly, when they got it and which variant). This also confuses things. Basically it's impossible to estimate.