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 |
|---|---|---|---|---|---|---|
| 131 | Algeria | 32.02 | 1.2 | 1.16 | 80.28 | |
| 132 | Angola | 32.38 | 0.31 | 1.1 | 80.91 | |
| 133 | Togo | 37.15 | 0.28 | 0.78 | 75.37 | |
| 134 | Zambia | 36.43 | 1.15 | 0.88 | 63.65 | |
| 135 | Senegal | 39.39 | 1.11 | 0.95 | 69.26 | |
| 136 | Mauritania | 38.71 | 1.64 | 1.08 | 62.39 | |
| 137 | Rwanda | 43.72 | 0.44 | 0.59 | 47.94 | |
| 138 | Sri Lanka | 42.37 | 0.47 | 1.01 | 63.15 | |
| 139 | Uzbekistan | 59.52 | 0.31 | 1.31 | 49.71 | |
| 140 | Guinea | 75.69 | 0.19 | 0.83 | 28.13 |