Effective Reproduction Number (Rt)
A series of reporting gaps/lags beginning in mid-November creates some instability in estimates during that period. However, the most recent data suggests an Rt spiking well above 1.0 in late November and early December. Significant volatility in estimates remains. Whether the recent increase in Rt signals the beginning of a sustained trend remains to be seen.
Because of the significant reporting gaps/lags described above, we modeled what the missing numbers most likely would have been during this period and project future cases over a two-week period based on a combination of these and more recent actual case numbers. It appears daily incidence will trend slightly upward over the coming weeks. Because these projections assume continued social mixing at levels seen in recent weeks, a post-holiday decline in mixing could portend lower-than-projected case levels.
Asymptomatic to Symptomatic Ratio
Data issues again complicate estimation, but the ratio of asymptomatic to symptomatic cases appears to have remained stable at a relatively low level since mid-December. A low ratio of asymptomatic to symptomatic cases facilitates mitigation efforts.