Conditional Herd Immunity
The basic reproduction number, R0, for COVID-19 is estimated to be 2.5. With this level of R0, herd immunity is reached when 60% of the population have been infected or recovered. During the COVID-19 epidemic, governments are encouraging/ordering the population to vary their behavior so that the effective value of R is considerably less than 2.5. This raises the prospect of a population reaching herd immunity with only 20% of the population being infected or recovered. This would be conditional herd immunity as it would be conditional on the population maintaining the lower value of R even after the number of infections starts to drop.
Based on a detailed analysis we present the countries listed in order of the expected time to reach conditional herd immunity.
| Rank | Country | Years to Herd Immunity | Immunity (%) | R values | TII (ppm) | Strategy |
|---|---|---|---|---|---|---|
| 41 | Ecuador | 0.04 | 18.37 | 1.08 | 4526.8 | |
| 42 | Greece | 0.06 | 17.74 | 0.95 | 5318.25 | |
| 43 | Germany | 0.09 | 17.41 | 0.89 | 4109.88 | |
| 44 | Iran | 0.09 | 16.11 | 0.92 | 5356.31 | |
| 45 | Ukraine | 0.1 | 17.96 | 0.64 | 2189.29 | |
| 46 | Netherlands | 0.1 | 16.99 | 0.99 | 3851.88 | |
| 47 | Tunisia | 0.12 | 16.6 | 0.79 | 3371.93 | |
| 48 | Lebanon | 0.23 | 17.7 | 0.72 | 1278.82 | |
| 49 | Costa Rica | 0.26 | 11.74 | 1.05 | 5044.25 | |
| 50 | Bahrain | 0.26 | 11.97 | 1.21 | 4428.94 |