In what may be a small glimmer of good news, this week has brought us decreases in new case and mortality rates as well as a decrease in prevalence of COVID-19 in Los Angeles County.
The volume of testing (Figure 1) has decreased significantly week over week from 1035 tests per 100,000 population to 702.
However, case and mortality rates both decreased week over week (Figures 2 and 3). These patterns would fit with increased household interaction over the Thanksgiving holiday. I suspect these numbers are less reflective of the new variant (B.1.1.7) which has been estimated to be 56% more infectious than typical. If indeed the B.1.1.7 strain had become more commonplace, we could expect to see a continued geometric rise in cases – rather than the usual bend, peak and decrease of the epidemic curve (Figure 2).
Prevalence too has decreased week over week from 20.1% to 18.4% (Figure 4) – and this is perhaps the most significant finding of all. The prevalence estimate accounts for the decreased testing volume and instead relies on test positivity rate.
The New Year has brought us a small amount of good news. I remain concern that we will have yet another bump because of Holiday travel. The next two to three weeks will tell the story.