Table 4.

Example for PPV, NPV, PSI, and NND as a Function of the Prevalence with 90% Sensitivity and Specificity.*

Prevalence (%) Estimated Prevalence PPV (%) FPF (%) NPV (%) FNF (%) PSI (%) NND=1/PSI
1 Iceland, Israel: Asymptomatic 8.3 91.7 99.9 0.1 8.2 12.2
5 Spain, Israel 33.1 67.9 99.4 0.6 31.6 3.2
10 50.0 50.0 98.8 1.2 48.8 2.1
30 New York City 79.4 20.6 95.5 4.5 74.9 1.3
50 Almost Herd Immunity 90.0 10.0 90.0 10.0 80.0 1.3
70 Herd Immunity 95.5 4.5 79.4 20.6 74.9 1.3
90 Most Infected 98.8 1.2 50.0 50.0 48.8 2.1
*This is an illustrative table. There are no reliable estimates of disease prevalence in various countries.
RMMJ Rambam Maimonides Medical Journal Rambam Health Care Campus 2020 July; 11(3): e0020. ISSN: 2076-9172
Published online 2020 July 31. doi: 10.5041/RMMJ.10412.