Figure 3: It appears that the current reproduction number (R_t) for Omicron is about 2.5, which is why it is outcompeting Delta in South Africa (current R_t <1). The dashed line shows immune escape vs. intrinsic infectiousness (R₀) for R_t = 2.5. Because most of the population now has pre-existing immunity from either infection or vaccination, Omicron may be outcompeting Delta either by virtue of higher intrinsic infectiousness (around 8 in the figure below) or higher immune escape (about 75% in the figure below). Adapted from Trevor Bedford (asamonitor.pub/31I145x).