Table 1.
Overall infection fatality ratio estimates among the included studies.
| Data | Model estimates | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Study location | Cumulative COVID-19 deaths | Reported Seroprevalence (dates) | Serostudy Sensitivity (%) (T+/D+ or 95% CrI) | Serostudy Specificity (%) (T−/D− or 95% Crl) | Crude IFR (95 CI%) | Sensitivity (%) (95% CrI) | Specificity(%) (95% CrI) | IFR without Seroreversion (95% CrI) | IFR with Seroreversionβ (95% CrI) |
| Brazil* | 51,179 | 2.42% (Jun. 04–Jun. 07) | 85.14 (81.93, 87.97) | 99.72 (99.55, 99.85) | 0.99 (0.92, 1.06) | 85.28 (82.12, 88.14) | 99.76 (99.62, 99.87) | 1.03 (0.93, 1.15) | 0.99 (0.89, 1.12) |
| Denmark* | 463 | 2.4% (Apr. 27–May 03) | 82.09 (75.51, 87.58) | 99.25 (98.94, 99.56) | 0.33 (0.23, 0.48) | 82.45 (76.11, 87.8) | 99.16 (98.73, 99.46) | 0.54 (0.38, 1.02) | 0.51 (0.36, 0.97) |
| England* | 48,301 | 5.94% (Jun. 20–Jul. 13) | 78.4 (65.68, 88.15) | 99.44 (99.11, 99.71) | 1.42 (1.39, 1.46) | 79.48 (68.74, 88.93) | 99.59 (99.34, 99.78) | 1.18 (1.02, 1.34) | 1.07 (0.84, 1.24) |
| Italy*, α | 34,610 | 2.44% (May 25–Jul. 15) | 96.04 (89.84, 99.05) | 99.7 (99.59, 99.79) | 2.3 (1.94, 2.72) | 96.42 (90.93, 99.13) | 99.69 (99.57, 99.78) | 2.53 (2.31, 2.78) | 2.40 (2.18, 2.63) |
| Netherlands | 5767 | 5.5% (May 10–May 20) | 98.28 (171/174) | 99.65 (281/282) | 0.6 (0.58, 0.63) | 98.23 (95.61, 99.52) | 99.83 (99.43, 99.98) | 0.62 (0.58, 0.69) | 0.59 (0.55, 0.65) |
| Spain* | 28,116 | 5.27% (Jun. 08–Jun. 22) | 81.84 (75.67, 87.01) | 98.79 (98.55, 99.02) | 1.12 (1.08, 1.16) | 84.72 (83.08, 88.36) | 99.05 (98.86, 99.21) | 1.14 (1.08, 1.22) | 1.08 (1.01, 1.16) |
| Sweden | 4992 | 7.1% (Jun. 08–Jun. 12) | 99.36 (156/157) | 98.89 (267/270) | 0.68 (0.46, 1) | 99.28 (97.23, 99.93) | 99.17 (98.12, 99.77) | 1.02 (0.87, 1.37) | 0.98 (0.83, 1.35) |
| Geneva, Switzerland | 262 | 10.84% (May 03–May 10) | 91.16 (165/181) | 100 (176/176) | 0.48 (0.42, 0.56) | 91.47 (87, 94.89) | 99.89 (98.82, 100) | 0.49 (0.42, 0.59) | 0.47 (0.4, 0.57) |
| Zurich, Switzerland | 124 | 1.59% (May 01–May 31) | 90.74 (49/54) | 99.89 (5,497/5,503) | 0.51 (0.45, 0.58) | 91.77 (83.39, 96.89) | 99.87 (99.74, 99.95) | 0.52 (0.41, 0.67) | 0.50 (0.39, 0.64) |
| New York State, USA* | 17,718 | 12.1% (Apr. 19–Apr. 28) | 89.39 (85.57, 92.55) | 98.73 (98.15, 99.27) | 0.75 (0.74, 0.76) | 89.66 (85.9, 92.68) | 98.7 (98.05, 99.2) | 0.78 (0.73, 0.84) | 0.76 (0.7, 0.81) |
The data columns (left) contain data and parameters used to calculate the crude IFR, the model columns (right) contain the posterior estimates from the full model. Citations for all the data sources are in Supplementary Table 2. The reported seroprevalences are listed along with the most recent dates for the seroprevalence survey. Cumulative deaths are summed to the mid-date of the most recent seroprevalence survey, and were usually confirmed COVID-19 test-positive patients except in England, which also reported probable COVID-19 deaths (individuals without test results but with COVID-19 on the death certificate). For the six studies with regional data, estimates of specificity and sensitivity were from analysis of regional data: posterior distributions with the median and 95% credible intervals are provided in place of the serologic test validation numbers (*). Model-estimated posterior sensitivity and specificity are indicated for the model with seroreversion, although these estimates were similar for both models (Supplementary Table 5). Overall IFR estimates were calculated by standardising the age-specific IFR estimates according to the inferred age-specific attack rate and the population demography with respect to the age groups used in the model (median, (95% Credible Intervals)). For comparison, the overall IFR estimates calculated by standardising for solely the demography and assuming the same attack rate in each age group are provided in Supplementary Table 3.
Serologic test performance is measured by the sensitivity and specificity (T+ test positive, D+ true positives, T− test negative, D− true negatives).
αSerovalidation data for the Italian serosurvey using the Abbott assay were not validated within the same study; here we used an alternative study testing the same assay.
βAssuming an extreme rate of seroreversion for sensitivity analysis based on the Abbott assay. The true seroreversion rates in these studies are unknown, but are likely less extreme, particularly if the Abbott assay was not used (only the Italy study used the Abbott assay.