ref.castedo.com/covid19/

Bounds for infection fatality rate (IFR)

This website uses 0.4% and 0.9% as low and high estimates for IFR.

Age-structure is an extremely important for IFR. The IFR for younger ages is significantly different than older ages. This is another reason to use low and high estimates rather than one single estimate.

How deaths are counted also makes a difference. Death counts on this website are based on "fast-and-easy" counts. Actual deaths due to the pandemic will likely be higher, maybe even double.

Some serosurvey results

Geneva, Switzerland
For all of Switzerland, stabalizing crude CFR of 5% to 6%. Confirmed cases Apr 1 to Apr 7 about 0.6% to 0.8% of Geneva population. Seroprevalence around Apr 21 is about 10%. Resulting implied IFR is about 0.3% to 0.5%. Repeated seroprevalence of anti-SARS-CoV-2 IgG antibodies in a population-based sample from Geneva, Switzerland
New York
Rough estimates of infection to death ratio. Remember that there is 1 to 3 weeks delay between infection and death or antibodies triggering positive test results. 
## Warning in structure(x, dim = dim(x)): Calling 'structure(NULL, *)' is deprecated, as NULL cannot have attributes.
##   Consider 'structure(list(), *)' instead.
## Error in zoo(structure(x, dim = dim(x)), index(x), ...): "x" : attempt to define invalid zoo object
## Error in names(frac) <- c("nyc", "up.river", "long.island", "nys"): object 'frac' not found
## Error in eval(expr, envir, enclos): object 'frac' not found
## Error in eval(expr, envir, enclos): object 'frac' not found
Apr 27 preliminary seroprevalence results:
nyc up.river long.island nys
0.247 0.151 0.144 0.149
(Apr 27 deaths) / (Apr 27 preliminary antibody results):
nyc up.river long.island nys
0.0057 0.0073 0.0077 0.0044
(May 1 deaths)/ (Apr 27 preliminary antibody results):
nyc up.river long.island nys
0.0061 0.0079 0.0083 0.0048
From Preliminary New York seroprevalence results. Finance professor estimates US IFR of 0.86% partly based on NYC serosurvey results: SARS-CoV-2, COVID-19, Infection Fatality Rate (IFR) Implied by the Serology, Antibody, Testing in New York City .
Santa Clara, CA
Results are too noisy. High estimate is infections are 55x cases (for IFR of 0.17%) from 2nd version of early study: COVID-19 Antibody Seroprevalence in Santa Clara County, California Other analysis indicated an order of magnitude fewer infections in the county: Estimating COVID-19 Antibody Seroprevalence in Santa Clara County, California. A re-analysis of Bendavid et al. and Estimation of SARS-CoV-2 Infection Prevalence in Santa Clara County
Iran
Small (525 samples) serosurvey in April estimates 22% to 33% infected, with an implied IFR of 0.12% to 0.2% based on confirmed COVID-19 deaths. Seroprevalence of COVID-19 virus infection in Guilan province, Iran

Some estimates WITHOUT serosurvey

China
Estimate of 0.66% IFR. Before serosurveys. Estimates of the severity of coronavirus disease 2019: a model-based analysis
USA
Estimates for March 31 to April 7 in New York (8.5%), New Jersey (7.6%), and Louisiana (6.7%). 12 population infections per diagnosed case. Estimating COVID-19 Prevalence in the United States: A Sample Selection Model Approach
Mexico/Iceland
Estimates of 0.33% to 0.5% IFR for Mexico and Iceland respectively. On the estimation of the total number of SARS-CoV-2 infections
Italy Initial Outbreak
IFR of 1.29%. An empirical estimate of the infection fatality rate of COVID-19 from the first Italian outbreak
EU
Estimates by Imperial College London based on dynamics of cases and deaths.

More References