Covid-19 in Fairfax County, Virginia, January 2023

To update my Covid report for Fairfax County to February 2023, the graph below continues the story from last month. There has been no significant winter surge as some had predicted, although there was a doubling of cases from the week after Thanksgiving through early January. Cases are again falling. Given natural daily variations, my model continues to track daily hospitalizations H and deaths D relatively well. Both H and D remain low, both in fact and in the model. My model assumes that actual cases are 4 times reported cases (via PCR tests) and there is 1 hospitalization for every 350 cases and 1 death for every 1000 cases. The actual H rate in January was only around 1 per day, about half that predicted by the model. Virginia state data indicate that over 90 percent of Covid deaths are now among those 65 years old or older (mostly over 80), whereas most cases propagate among those under 65

Feb. 2, 2023. The points show daily case (blue), hospitalization (green), and death (red) data for Covid-19 in Fairfax County, Virginia, between May 1 (day 305), and Jan. 31, 2023 (day 580; source: Virginia Department of Health, VDH). The case numbers here are assumed to be FOUR TIMES the reported cases confirmed by reliable PCR tests; this provides an estimate of untested or home-tested cases based on assuming an unchanged hospitalization rate from earlier data before home testing was widely available. The solid blue, green, and red lines show 7-day average data. The light green and red lines show my model predictions, assuming a hospitalization rate of 1 in every 350 actual cases and a death rate of 1 in every 1000 actual cases, delayed by 5 weeks (35 days) from case onset.