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 |
|---|---|---|---|---|---|---|
| 151 | South Sudan | 283.47 | 0.17 | 0.96 | 10.82 | |
| 152 | Cote d'Ivoire | 259.09 | 0.18 | 0.8 | 7.56 | |
| 153 | Ghana | 266.49 | 0.41 | 0.68 | 7.93 | |
| 154 | Burkina Faso | 269.15 | 0.13 | 1.11 | 9.67 | |
| 155 | Niger | 302.03 | 0.14 | 1.16 | 8.86 | |
| 156 | Sierra Leone | 290.98 | 0.16 | 1.51 | 10.3 | |
| 157 | Uganda | 582.55 | 0.13 | 1.13 | 4.53 | |
| 158 | New Zealand | 658.28 | 0.09 | 0.35 | 2.73 | |
| 159 | Nigeria | 781.5 | 0.17 | 0.91 | 2.94 | |
| 160 | Vietnam | 2343.79 | 0.01 | 1.1 | 1.07 |