Covid-19 in Fairfax VA, 2020-2022

The Big Picture: 2022 is not like 2020

The graph below summarizes all the data I have from the Virginia Department of Health (VDH) on daily cases (C), hospitalizations (H), and deaths (D) from the beginning of Covid-19 records in March 2020 through July 2022, covering over 800 days of data. I divide this “big picture” into two phases, divided by “Day 0” on the graph, June 30, 2021. Phase 1 from March 2020 through June 2021 represents the pre-vaccination phase (vaccinations began in earnest in Feb. 2021 and by June 30, 2021, 62 percent of Fairfax residents had by vaccinated with 1 or more doses). Phase 2 represents the propagation of new variants among a mostly vaccinated population. Hospitalization and death rates show a marked difference between the two phases, dropping around ten-fold in the second phase from those that applied in the first.

The points show daily case C (blue), hospitalization H (green), and death D (red) data for Covid-19 in Fairfax County, Virginia, between March 17, 2020 (day -470), and July 31, 2022 (day 396); source: Virginia Department of Health, VDH. The break between phases is arbitrarily set at Day 0, June 30, 2021, near where cases were at an absolute minimum. The case numbers only include cases confirmed by reliable PCR tests and thus do not count untested or home-tested cases. The solid blue, green and red lines show 7-day averages of the data. The dashed blue line in the upper panel shows my model of actual cases based on a fixed ratio of cases to hospitalizations H, since initially the latter could be counted much more accurately than the former. In Phase 1, the H and D rates were 1 in 33 cases and 1 in 200 cases respectively, whereas in Phase 2 H and D had improved to 1 in 380 cases and 1 in 1500 cases (see analysis for my model assumptions).

Phase 1-then

Phase 1 includes two “waves” of cases. The first was the initial ramp-up in cases in the spring of 2020. The second was the November-February “Thanksgiving and post-Christmas” wave in the winter of 2020-2021. At the peak of the first wave, Fairfax was experiencing over 25 hospitalizations per day and over 10 deaths per day. The corrected case model (see below) estimated Fairfax was actually having around 1000 cases C per day at the peak of the first wave. The second wave was longer in duration but with a lower peak case rate nearer 500 per day

Since cases were undercounts in the early months because widespread testing was just starting to be deployed, I constructed a model of actual cases based on the known number of daily hospitalizations H. The model assumed a fixed ratio of 1 H for every 33 cases. This fixed ratio accurately tracked the 7-day average of C and H data for Fairfax from March 2020 to March 2021, after which widespread vaccination began to occur in Fairfax. A similar fixed ratio of 1 death D for every 200 cases, occurring 14 days after case onset, accurately tracked the death data for Fairfax County through March 2021. This death rate is 5 times higher than that for the familiar seasonal flu. This death rate for Fairfax was also much lower than that for the USA as a whole, where the rate was closer to 1 in 50 cases in this first phase, a rate 4 times higher than in Fairfax. Most of the people who died in Fairfax County were in the older 65+ age group of the 4 age ranges tracked. The data show that in the first year, 70 percent of the cases were for younger people under age 50, whereas 82 percent of the deaths were for the oldest 65+ part of our population. Thus, the disease primarily propagated among more active younger people, whereas it was the oldest people who did the majority of the dying. In Phase 1, if you were over age 65 and got Covid-19, the odds you would die were 1 in 9 cases, kind of like playing Russian roulette! (The actual data are 945 deaths out of 8214 cases among those age 65+ between March 2020 and July 2021).

Phase 2-now

Phase 2 of the pandemic in Fairfax has seen three “waves” of cases due to the onset of different variants of the underlying Coronavirus. At the start of Phase 2, C, H, and D had all reached low points, with an average of less than a dozen cases per day by “Day zero,” the end of June 2021. This was the time when Fairfax County had reached 62 percent of its population with 1 or more shots of the new vaccines. The new more contagious Delta variant caused a surge in cases to around 200 per day in the late summer/early fall of 2021. The very contagious Omicron variant caused a very rapid ramp-up in cases in December of 2021, peaking at an all-time-high average 2500 cases per day in mid-January, 2022, followed by just as dramatic a fall to less than 100 cases per day in early March 2022. Cases begin to rise rapidly again in late March, reaching a peak near 600 cases per day in late May. The case rate has remained relatively high since then, with a slow decline to around 350 cases per day by the end of July 2022.

Fortunately, the H and D rates in Phase 2 have improved dramatically relative to those in Phase 1. Presumably this is due to two factors: vaccinations and more people with some natural immunity from having the disease: 91 percent of the population of Fairfax County has been vaccinated with at least 1 shot, and 20 percent of our population has already had Covid-19 according to the official count (227,000 total cases out of a population of 1.15 million). It is also possible that the new variants represent a milder form of the disease, although this is not clear. The new variants definitely have less impact since most people have some antibodies already in their bodies. The H and D rates during the Delta wave were two times better than in Phase 1 (1 in 70 cases for H and 1 in 360 cases for D during the Delta “wave”). They improved even more by the Omicron wave, where H was 1 in 380 cases and D remained about the same. The ten-fold improvement in the hospitalization rate was especially dramatic

The current “wave” due to new very contagious variants of Omicron does not have a well-defined peak, but a long period of relative stasis and stagnation. Cases remain high, and we have been having over many weeks now a relatively constant number of around 4 daily hospitalizations and 1 daily death. Given the official case rate, these would represent a serious increase in the H and D rates relative to the winter Omicron wave. But I believe that there is a better explanation. The VDH case number C only represents positive PCR tests (those that go to a lab and are usually reported back to you the next day) and do not represent home-tested or untested cases. Given so many mild cases, and the widespread availability of home tests, I prefer to assume that the current official case rate C represents a large undercounting of actual cases. If we assume that the SAME H rate applies now as during last winter’s Omicron surge, then the number of cases per day would not be around 400 to 500, as reported during the last few months, but would be 3 times higher, around 1500 cases per day. If this is so, we can account for the current number of daily hospitalizations and deaths assuming rates of 1 H per 380 cases and 1 D per 1500 cases, consistent within model for H during the winter surge and showing a four-fold improvement in the death rate. Thus, H and D are both showing a ten-fold improvement now relative to their values in Phase 1.

With the above assumptions, the current death rate of 1 per 1500 cases is less than the 1 per 1000 cases of the seasonal flu. The hospitalization rate is also relatively low, over ten times lower than during Phase 1. Consequently, Covid-19 in Fairfax may have entered an endemic phase where it still circulates widely with a high number of cases, but with relatively minor impact on most people, comparable to a normal season of the flu. Of course, this is the situation this summer, and we need to see what happens this fall and winter.

I would like to comment on why we might be having this “endemic surge” in cases now. One reason may be the presence of much more contagious variants. However, I also notice that cases began to rise shortly after mask mandates were removed from Virginia schools in early March and as more and more people began to mingle more with less masking. The first was a new policy by order of the Governor, whereas the second just represents my personal observations. I am not commenting on whether these actions are “good” or “bad,” since either of such judgments would be too simplistic to be helpful. It may be that people are just sick of masking and other restrictions, and since the disease seems not to be “too bad” for most people to risk, therefore most people are taking far fewer precautions than they had been doing. This scenario seems plausible to me. This may be the right time to “lighten-up” on cautionary restrictions (but not all).

If one is under age 50, even age 65, there is now very little danger of dying from Covid-19, even if one gets somewhat sick from it. Virginia State demographic data show clearly that most people who are now dying from Covid-19 are actually over 80 years old–it is several times safer to be in the 70-79 age group than to be over 80. In the most recent quarter (13 weeks), there have been 1148 cases and 35 deaths in Fairfax County of people 80+ years old. This represents the majority of deaths in the County, and a rate of 1 death for every 33 cases in the 80+ group. The same 80+ death rate applies to the state of Virginia as a whole. This rate is already better than 3 times lower than the rate (1 in 9) for those 65+ in Phase 1. So all age groups seem to be better off now than they had been then. So 2022 IS NOT LIKE 2020. That is the good news. But 1 in 33 odds is still not great–so our oldest citizens would still be prudent to take precautions against catching this still dangerous disease. The best current reason for younger people to take some precautions is to lower the overall rate of spread so there are fewer total cases in circulation, including among the elderly. And CDC data show that the odds of catching Covid-19 or of becoming seriously ill or dying from it are still much worse if one in unvaccinated, so keeping up to date on vaccines and boosters is still the wisest course for everyone who is medically eligible to receive them.