Update on February 17th. I had expected peak deaths to occur this week or the previous week, and thought they might go as high as 6,000 per day, based on the ratio of deaths to cases in South Africa and the number of new cases America was experiencing in early January. About a week after I modeled this death rate, new findings out of the UK showed me that Omicron was about half as deadly as it appeared to be simply from looking at case counts and deaths in South Africa. So, I suspect the South African case counts were significantly undercounting infections, and something about the population in the UK and USA made Omicron less deadly here. We did hit a seven-day daily death average over 3,500 last week, and as I write this update on February 17th, the seven-day daily death average is at 2,200. Given that the UK research showed omicron to be half as deadly as the South African numbers suggested to me, this death rate seems to match revised expectations. The main point I wanted to make with this post was that the mild form of omicron would still kill horrifying numbers of persons, given how widespread infections were, and the death numbers we have had last week and this are approximately equivalent the highest death rates the pandemic generated in the USA, almost exactly a year earlier.
People should remember that “mild” as a term describing COVID-19 or SARS-CoV-2 infections doesn’t mean the same thing that “mild” means in normal usage. Severity of an illness can be measured by symptom counts, or by severity of symptoms as rated on some scale, or by mortality (deaths) attributed to the illness. “Mild” in terms of pandemic terminology means that an illness is not severe enough to send someone to the hospital or kill them. Probably most of us have experienced illness that would be “mild” according to this standard, but still seemed pretty severe. Maybe we’ve had a flu or some other illness that briefly had our temperature up to 40°/104°, but we didn’t go to a hospital for it. Or maybe we couldn’t keep food down for several days, or couldn’t get out of bed for a week, or had a case of pneumonia or strep throat that was treated by a visit to the doctor’s office rather than a hospital admission. Those illnesses were all “mild” in the sense that they didn’t send us to the hospital. Also, the mildness of an acute case of COVID-19 may not (or may) have a bearing on whether a person develops Long COVID. Long COVID is mild, but it’s awful. A few of the persons suffering some of the worst cases have been driven to commit suicide by it. Some estimates are that 10% of persons contracting COVID may develop Long COVID, even if they had asymptomatic SARS-CoV-2 infections without developing COVID-19.
Case fatality rates in the USA (not infection fatality rates) have been between 1.5% and 2% in recent months, although they seem too be declining toward 0.9% now, and if we assume only a third of SARS-CoV-2 infections are reported and made into “cases” we can say mortality rates per infection (not per case) are going down from 1-in-200 being fatal to 1-in-300 or 1-in-400 being fatal. But, given how Omicron SARS-CoV-2 is spreading, even this steep decline in lethality will not spare us from new levels of death we can expect in February to surpass the worst we have experienced so far.
I’ve just examined some charts related to COVID at the 91-DIVOC site, and I want to share them here and comment on them. First of all, let’s look at the good news, the chart of case mortality:
 |
| Deaths per case of COVID, Illinois highlighted, smoothed by monthly averages |
I’ve highlighted my state of residence, Illinois, but please remember that each state has a somewhat unique pattern of case fatality rates. For example, about two months ago as I write this (mid-January 2022) Oklahoma and Georgia were having case fatality rates of 6% to 7% while Illinois was having fatality rates of 1%. This chart is a bit confusing because we don’t really know what “case” means. I think it cannot possibly mean “infection” and probably instead means either “known infections detected through testing and reported to public health authorities” or else “persons admitted to hospitals who were tested and found to have COVID-19 symptoms and tested positive for SARS-CoV-2 exposure”. It might even mean “persons admitted to hospitals who were admitted for COVID-19 and tested positive for SARS-CoV-2 exposure”. Perhaps it means different things in different states. I don’t know.
Deaths per case of COVID, USA average highlighted (smoothed as one-month averages)
Another issue is that the fatality rate isn’t very smooth, and isn’t showing a clear downward trend (except for the past month or two, as Omicron spreads, but then again, we’ve had fatality rates fall before, in August of of 2020, in April of 2021, in August of 2021, etc.). You might think along these lines: initial waves of COVID-19 killed the most vulnerable persons who were infected, and in the first months of the pandemic, medical staff didn’t know how to best treat COVID-19, and early in the pandemic, no one was vaccinated. As more people are vaccinated, and as medical journals share more information about treatments that really are effective, and as younger and healthier people get the disease (because more vulnerable persons have already had it or have died from it), you might expect a trend of decreasing fatality rates, but we don’t really have that consistently; just five periods of decline in rates of death per case, with the most recent one (which we’re still in) being of a long duration and reach the lowest rate yet seen.
Keeping in mind that it takes an average of two or three weeks from the time a person is admitted to a hospital with COVID (a new case of COVID is identified), you might guess that the spikes in fatality rates per case might occur a few weeks after spikes in new cases. As new cases flood the hospitals, probably treatment suffers and that would drive up fatality rates, right? Well, that’s not quite what has happened. The first fatality spike was in April and May of 2020, a few weeks after the initial case spikes in March and April of that year. There was a “little” spike in cases in July of 2020, and there was no ensuing spike in fatalities in August. There was, however, a spike in fatality rates in September of 2020 experienced in several (but not most) states, and there wasn’t really any spike in new cases in August to explain it. Illinois, which is highlighted in the chart, didn’t see the case or fatality rate spikes in late summer and early autumn of 2020.
The winter of 2020-2021 was a terrible time for new cases, with the biggest jump in new cases we have seen until the recent Omicron spike. Fatality rates climbed a little in December and January, but really spiked in late February and early March. What does that mean? That is a strange lag, well over the standard three weeks, so what could explain that? The last people to get sick in a spike are more likely to die, evidently, or at least that seems to have been so in early 2021. Maybe the type of COVID people suffered in the winter of 2020-2021 just took longer to kill people? Higher fatality rates per case should mean that the type of SARS-CoV-2 is more lethal, or it’s infecting people who are more vulnerable, or the quality of care is not as good. In February and March of 2021 we weren’t suffering a spike in new cases three weeks earlier (we more like five-to-eight weeks earlier), so were the people getting sick in mid-spring of 2021 just more vulnerable, or was a more lethal strain on the loose?
In May and June of 2021 we achieved our lowest level of new cases since the start of the Pandemic—we were experiencing about 12,000 new cases per day in June of 2021, whereas as I write this with Omicron in full swing we are seeing about a million new cases per day. And yet the summer of 2021 is a time when fatality rates spiked to levels almost as high as they had been in the fist months of the pandemic. This was evidently a combination of two causes that drove up fatality rates: the Delta variant was becoming dominant, and it was more lethal, and over half of the vulnerable population susceptible to mortality from COVID had recently completed their second injection of vaccines, so the persons who had virus exposure and developed COVID were more likely to be entirely unvaccinated. Yet, in August we had a steep decline in mortality rates, and only a low rate of increase of mortality rates per case in September, despite a relatively sharp spike in cases experienced in August. By late October and early November fatality rates were again relatively higher, but “high” mortality rates of 1.5% to 2% in the autumn of 2021 were as good as the “low” rates of morality experienced in April of 2021 and November of 2020.
We’re now at the lowest rate of morality yet observed, below 1%. The trend is continuing to go down in mortality rates. Clearly we’re seeing the effect of vaccination boosting and the lower mortality of the Omicron variant. But, let’s look at the next chart, which shows new cases per day (weekly averages):
 |
| New COVID Cases (smoothed as one week averages) |
This shows the spikes we have had in COVID cases. In April of 2020 we had the initial spike, with terrible outbreaks in New York, New Jersey, and some other New England states. In July of 2020 we had a second spike largely concentrated in Florida, Texas, and California, with Arizona and Georgia also suffering. The winter spike of November 2021 to January of 2021 was a three month terror that hit California, Texas, New York, Florida, Arizona, Ohio, Pennsylvania, and Tennessee especially hard. There was a small spring spike in late March and April of 2021 that hit New York, Michigan, Florida, and Pennsylvania. There was a Delta variant spike in August and September of 2021, hitting Florida, Texas, California, Georgia, and Tennessee especially hard. Michigan had its own little spike in November, and then in mid-December the cases began to climb in the current massive and unprecedented spike of Omicron.
The next chart, which shows fatalities per day, uses a line for the USA as a whole to show what was going on:
Daily deaths from COVID in the USA (smoothed to one-week averages)
You can see how the spike in deaths in September and October follows the spike in new cases (seen in the previous chart) of August and September. Likewise the spike of new cases in November 2020 to January 2021 led to a spike in deaths in December of 2020 to February of 2021. The Omicron new infection spike began in mid-December, and you can see that the spike in new deaths per day began around January 6th or 7th, right on schedule.
Considering that there is a two-to-three week lag between new cases and deaths, we will need to wait until two or three weeks after we reach the peak of new cases before we can hope to see death counts decline. Just this week the new case counts (averaged by 7-days) are about double what they were two weeks ago (900,000 in this second week of January compared to a little less than 500,000 in late December). In early-to-mid December with about 120,000 new cases per day, we suffered about 1,200 to 1,600 deaths per day in late December and early January: a fatality rate of slightly over 1%. Assuming we hit the top new infections late this month with an average of about 1.2 million new cases per day, and assuming the cases contracted in mid-to-late January are substantially less lethal than cases contracted in mid-to-late December because of a higher percentage of Omicron in the mix (and higher rates of vaccination and previous exposure to SARS-CoV-2 infection), we can estimate that death counts in mid-February will be about 6,000 per day.
That’s right, the Omicron with a much “milder” and “less lethal” situation per each case seems likely to inflict death rates in mid-February 2022 that will exceed the highest death rates so far seen (in January of 2021) by a factor of two. With so much more enhanced immunity in the population and a much less lethal virus variant, we still are likely to witness a significant portion of February where death counts will be around 6,000 per day, compared to the 3,000 per day we endured in January of 2021.
That is what a milder version of a virus can do if it is far more contagious.
The grim daily increase in COVID cases, even with milder Omicron, is terrifying
Who will these 6,000 people per day be? About 5,500 of them each day will be unvaccinated, and well over 400 will be persons who only received one or two injections without getting a booster vaccination. Most of the rest will have factors that make COVID worse, such as obesity, vitamin-D deficiencies, HIV+ status, cancer, or other risk factors that for an unlucky few will make death a (fairly unlikely) possibility even if fully vaccinated and boosted.
No comments:
Post a Comment