I’ll see if I can find the comparative subject overview paper. It was published about 10 years ago. It might be cited in this paper.
The 1 out of 10 reporting rate sounds plausible simply because it is so difficult to create a passive system that captures a larger percentage of these events. And because at least half of these events will be delayed action. Based on what is seen in adverse response distribution in clinical trials. About 50% immediate, the other 50% over the following 3 month to a year. Quite separate from the usual problem of determining primary cause of death in so many cases.
The main purpose of these systems is not to record every event but to flag sudden upsurges and spikes in adverse response events. The are designed to try and make vaccines safer by putting a place some kind of tripwire to catch problems early.
So people who claim that VAERS cases are not proved to be caused by the SARs 2 vaccines are at best ignorant or usually just willfully stupid. Thats not its function. Which is why I have always used it comparatively. Comparing the SAR2 vaccine numbers versus the annual flu shot. Same system, same methodology, same type of viral infection, lower health risk from SARs 2, but spectacularly different mortality numbers. By this stage the majority of all deaths in VAERS over the last 30 are from the last 8 months of mass inoculation with the SAR2 vaccine.
That I think tells us something.