Covid-19 in Fairfax County, Virginia, January 2022

January 21

The Covid situation in Fairfax continues to improve, with cases dropping now and hospitalizations and deaths remaining remarkably low throughout the recent surge. While the 7-day average of new daily cases stands at 1500, still higher than at any time in the pandemic prior to late December, the number of hospitalizations is only around 3 per day and the number of reported deaths is only 1 every few days (“few” is 3 to 7, but there are two few events to extract a meaningful number). Hospitalization rates (1 in every 380 cases) are 5.4 times lower than during the Delta surge in August and September; the death rate (1 in around 4000+ cases) is more than 10 times lower than for Delta and is now significantly lower than that for the seasonal flu (around 1 in 1000 cases).

Jan. 21, 2022. The points show daily case, hospitalization, and death data due to Covid-19 in Fairfax County, Virginia, between July 1, 2021, and Jan. 14, 2022 (source: Virginia Department of Health, VDH). Case levels are undercounts since they only include cases confirmed by reliable PCR tests and do not count untested or home-tested cases. The solid blue, green and red lines show 7-day averages of the data. The light green and red lines show my model predictions as described in a previous post. The magenta line shows the Delta + Omicron double exponential model described previously, now using an Omicron case doubling time of 4 days to best fit the data through Dec. 31. The “width” of the Omicron curve looks like it is going to be around 3 to 4 weeks, in contrast to the 8-week duration with previous variants. We do not yet know what the “tail” of the curve will be–how quickly will cases drop back to a relatively low number?

The hospitalization and death rates for Fairfax County are MUCH better than in most parts of the USA, where daily hospitalizations are around 1 in 30 cases (28,000 new daily admissions for around 700,000 daily cases) and the death rate is around 1 in 350 cases (2000 daily deaths in around 700,000 daily cases). The strangely high hospitalization rate (1 in 30 cases), which is similar to the high rate we saw in Fairfax in 2020, suggests to me that cases in the USA as a whole are likely being significantly undercounted, that is, there likely are a million or more unreported daily cases which are needed to account for the number of nationally reported hospitalizations.

January 15

Now that we are 2 weeks into 2022, it is clear now that the recent Covid surge in Fairfax is slowing and may be ready to turn down. You can look at the case data in the graph below. Starting in early December, Covid cases rapidly increased from an average below 200 per day to a never-before-seen average above 2000 per day by the end of December and have flattened since then. It is clear that we are no longer in an exponential rise situation. Hopefully a downward trend in the 7-day average is starting and will continue. The good news is that hospitalizations and deaths in Fairfax are remaining relatively low throughout this recent surge in cases.

Jan. 15, 2022. The points show daily case, hospitalization, and death data due to Covid-19 in Fairfax County, Virginia, between July 1, 2021, and Jan. 14, 2022 (source: Virginia Department of Health, VDH). Case levels are undercounts since they only include cases confirmed by reliable PCR tests and do not count untested or home-tested cases. The solid blue, green and red lines show 7-day averages of the data. The light green and red lines show my model predictions as described in a previous post. The magenta line shows the Delta + Omicron double exponential model described previously, now using an Omicron case doubling time of 4 days to best fit the data through Dec. 31. The graph shows that Fairfax is no longer in an exponential doubling mode..

Hospitalizations remain stable at around 5 or 6 new ones per day. This corresponds to a much lower hospitalization rate of around 1 in 440 cases, which is a 7 times lower rate than the 1 in 70 cases that has characterized the Delta surge from July through November. If the higher rate applied now, we would be seeing over 30 hospitalizations per day now.

It is not clear if the small number of reported deaths, 7 in the last week, is the final number, since VDH has said that use of new reporting criteria could lead to a delay in reporting in January. VDH reported no deaths in Fairfax for the first week of January. Of the 7 last week, 6 were in the 65+ age group, consistent with the roughly 80 percent of deaths coming from this older age group throughout the pandemic. The relatively low death rate, 1 per day, is similar to what we were seeing prior to December and shows no evidence for any significant increase in deaths. While the number of deaths is too small to get accurate ratios due to statistical fluctuations, the data from this past week indicates a rate of 1 death in 1800 cases, which is a lower rate than that for the seasonal flu and 5 times better than the 1 death in 360 cases that applied to the Delta surge last summer and fall. If the latter Delta rate applied now, we would be seeing around 5 deaths per day in Fairfax now, instead of actual one per day in the VDH data from last week.

If these numbers continue to hold, it will be clear that the current variant driving the surge causes a much milder disease in everyone than earlier variants. The current rates of hospitalization per case and death per case are roughly ten times smaller than they were in 2020 before there were any vaccinations. However, VDH data for all of Virginia clearly shows that by far the largest number of current cases and most of the hospitalizations and deaths are among the unvaccinated, for which the population is 6 times smaller than for the vaccinated population in Virginia. Thus the lower overall rates implies that lower rates would also apply to the majority of cases that are due to the unvaccinated. Vaccinated people can expect to do even better. It is only the sheer number of cases among the unvaccinated that causes concern and harm.

Fairfax is currently 87 percent vaccinated with at least 1 shot and 77 percent fully vaccinated with 2 (or more) shots. If the case rates for vaccinated and unvaccinated people in Virginia as a whole apply here, then 86 percent of the recent cases in Fairfax would be due to the minority unvaccinated 13 percent of the population(150,000 unvaccinated), which has a 40 times higher per capita case rate than the larger vaccinated 87 percent of the population (1 million vaccinated). The age group with the largest number of cases in Fairfax County is the under 50 age group, which has nearly 80 percent of the cases and which is the least vaccinated age group in Fairfax. It pays to get vaccinated. It helps everyone.

It is good news that the new variant has turned out to be relatively mild. Otherwise, Fairfax would be in trouble now, like many other places with much larger unvaccinated populations to push up cases that threaten to crash the health care system for everyone. Fortunately, Fairfax is doing relatively well, as it consistently has done throughout the pandemic.