Covid-19 in Fairfax County, Virginia, December 2022

The graph below updates my running account of Covid-19 in Fairfax County, Virginia, using the new model I had introduced in October 2022, in order to interpret the available data from the Virginia Department of Health (VDH). The model assumes that reported cases from VDH, based on positive PCR tests, represents an undercount of actual cases by a factor of 4, and that the hospitalization and death rates have remained constant at 1 in every 350 actual cases and 1 in 1000 actual cases, respectively.

The blue line in the upper panel shows that cases have steadily declined from May through November, followed by a rapid increase in the number of cases starting the Monday after the Thanksgiving holiday. This may be the beginning of a widely expected “winter surge” in cases. Time will tell. New daily hospitalizations and deaths remain low in Fairfax County, fluctuating between around 2 to 6 per day for the former and 1 to 2 per day for the latter. The hospitalization rate seems to be tracking the rise in cases, but daily variation may be obscuring the trend. Since deaths follow case onset by around 4 to 6 weeks, I do not expect an increase in deaths to show up until the new year. My model predictions continue to track the actual hospitalization and death rates fairly well (within normal daily variation), except that actual hospitalizations tend to be higher than the model predictions. The model death rate is comparable to that from the seasonal flu, assuming that my factor of 4 scaling ratio of actual to reported cases is correct.

Dec. 18 2022. 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 Dec. 17, 2022 (day 534); source: Virginia Department of Health, VDH. The case numbers here are 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.

Fairfax has stopped reporting deaths by age group. However, data from earlier months and from state and national data indicate that almost all the deaths in recent months, 90 percent or more, are occurring for people age 65 and older. Most of the deaths for those over 65 come from the 80+ age group. Covid-19 propagates mostly among younger people but kills mainly older people. According to data that was available earlier (before Fairfax stopped reporting deaths by age group and before Virginia stopped reporting deaths by vaccination status), if one is over age 65 and contracts Covid-19, the odds of dying are 1 in 10 (!!!) if one is unvaccinated and closer to 1 in 50 to 1 in 100 if one is fully vaccinated. Very few people under 50 are now dying of Covid-19. Complications such as long-Covid including long-term fatigue and other more serious side effects remain a concern for all age groups.

How do you best protect yourself, if you choose to do so (many people now think it is not worth the trouble)? Case transmission is mainly by airborne particles that accumulate in crowded indoor spaces, especially if there is inadequate ventilation or air circulation. A measure of protection is available by several well-tested means: avoiding such spaces, masking, or opening windows or doors to provide better ventilation, and, of course, having antibodies via vaccination/boosting or by having had Covid recently.

The “big picture” analysis of all cases in Fairfax County, VA, between March 2020 and August 2022 is at this Link