A rough scale of the relative merit or demerit of something might look like this:
desired risk (low or no risk)
acceptable risk
unacceptable risk
intolerable risk
For the original DTP (diphtheria-tetanus toxoids-whole-cell-pertussis) vaccine, risk was unacceptable. The unacceptable level of risk led to the invention of acellular pertussis vaccines, such as in DTAP (diphtheria-tetanus toxoids-acellular-pertussis) vaccine.
In 1992, 19.5 million doses of DTP were given, and only 1.7 million doses of DTAP were given (~0.1 doses of DTAP for every dose of DTP). But by 2001, 18 million doses of DTAP were given, and only 67,903 doses of DTP were given — or about 265 doses of DTAP for every dose of DTP.
Replacing DTP with DTAP “worked” in that it cut the rate of serious adverse event reports — or serious AE reports — down from 48 per million doses (DTP) to 19 per million doses (DTAP).
While still above the overall average of 9.6 serious AE reports per million doses, 19 per million is better than 48 per million.
Keeping in mind that, for diseases like pertussis (whooping cough), 48 serious adverse events was an unacceptable level of risk, we can compare it to the risk of a serious AE from Moderna shots.
It appears that 44,477 serious adverse event reports were filed with VAERS, but that, in some of them, more than one serious AE was found per person (and even more than one vaccine type per person).
Adding up all of the serious adverse events found for Moderna brings the total up to (52,908+1,220=) 54,128 serious AEs. And here is the uptake level for Moderna:
When you divide the 54,000+ serious adverse events by the 251+ million Moderna shots given out by that time, you get a rate of 215 serious adverse events per million Moderna doses.
But that is more than quadruple the unacceptable serious AE rate of 48 per million (for DTP vaccines).
If 48 serious AEs per million doses is unacceptable, then 215 serious AEs per million doses ought to be that much more unacceptable — if the diseases are even remotely comparable.
The middle 50% of estimates for capture rates of passive surveillance systems like VAERS runs from 2% capture of underlying events up to 18% capture (under-reporting rates from 82%-98%).
At 2% capture of the actual events occurring in the background, the Moderna AE reporting rate indicates (215*50=) 10,750 serious AEs per million doses. That’s one serious AE (requiring hospitalization or worse) for every 93 Moderna shots.
Because public policy is supposed to account for worst-case scenarios, officials should incorporate the plausibility that 1 in every 93 recipients of Moderna shots gets hospitalized from it.
Reference
[DTP vaccine produces 4.8 serious AE reports per 100,000 doses (48 per million), but the average for all vaccines is 9.6 per million] — CDC. https://www.cdc.gov/mmwr/preview/mmwrhtml/ss5201a1.htm
[~48 serious AE reports per million doses is unacceptable] — Decker MD, Edwards KM. Acellular pertussis vaccines. Pediatr Clin North Am. 2000 Apr;47(2):309-35. doi: 10.1016/s0031-3955(05)70209-1. PMID: 10761506. https://pubmed.ncbi.nlm.nih.gov/10761506/
[passive surveillance captures 2% - 18% of the actual, underlying adverse events] — Hazell L, Shakir SA. Under-reporting of adverse drug reactions : a systematic review. Drug Saf. 2006;29(5):385-96. doi: 10.2165/00002018-200629050-00003. PMID: 16689555. https://pubmed.ncbi.nlm.nih.gov/16689555/