Studies in Stanford CA, Rome and Montreal suggests...
40 eligible national seroprevalence studies, covering 38 countries with pre-vaccination seroprevalence data.
For 29 countries publicly available age-stratified COVID-19 death data, and age-stratified seroprevalence information were available, and were included in the primary analysis.
Infection Fatality Rate (IFR) for 0 to 59 years
median IFR = 0.035%
(IQR, 0.013 - 0.056%)
Without accounting for seroreversion(average time from seroconversion to seroreversion at 3-4 months)
IFRs for 0 to 69 years
IFR = 0.095%
0 to 19 years
IFR = 0.0003%
20 to 29 years
IFR = 0.003%
30 to 39 years
IFR = 0.011%
40-49 years
IFR = 0.035%
50-59 years
IFR = 0.129%
60-69 years
IFR = 0.501%
At a global level, Pre-vaccination IFR, may have been as low as:
0 to 59 years = 0.03%
0 to 69 years = 0.07%
The current analysis suggests a much lower pre-vaccination IFR in non-elderly populations than previously suggested.
Large differences did exist between countries and may reflect differences in comorbidities and other factors.
/b]
https://www.medrxiv.org/content/10.1101/2022.10.11.22280963v1