A big part of the problem is the delay before autopsy. In larger cities, along with the Fentanyl mortality and gang homicides, it might take months to get a conclusion.
Further muddying the water is that vaxx related mortality might come from a dozen different “proximate causes”. And then it might be an original cause, or lethal aggravation of a pre-existing condition.
I’m not saying the problem is insurmountable, only that it is going to be very difficult to figure it out.