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A look at Sweden, and new developments on herd immunity

It’s been a week since my last report, and a lot has happened. But first, Sweden. If you’ve followed COVID news at all, you know that Sweden’s approach to the pandemic has been wildly controversial. Rather than impose restrictions to slow the spread of the virus, Sweden pretty much let people behave as they liked. They did impose a few restrictions, but nothing close to the response of the rest of the world. I can show you countless articles declaring Sweden a success, and an equal number citing it as a disaster. I confess that until now I’ve not even looked at Sweden’s data, but I needed to satisfy my curiosity, so here goes…

I couldn’t find a single source modeling active cases in Sweden, so I ran Johns Hopkins’ data through my model, and see this:

This surprised me for a number of reasons. First, Sweden peaked later than I would have guessed, on June 29th. Also, the peak is relatively low, at 0.085% of the population. They didn’t have nearly the reported COVID numbers I would have expected. Here is where Sweden stacks up against the 15 states that I follow:

This is stunning to me. Sweden (SE) is the next to lowest on my list. Why so low? We find a clue in an antibody study from mid-May in Stockholm. 7.3% of those tested had COVID antibodies. At that time, there were 29,192 documented cases in Sweden, or 0.29% of the population. This implies that the total prevalence was something like 25 times larger than the documented cases. (Yes, I’m extrapolating Stockholm to the rest of Sweden, but I’m just trying to ballpark things here.) Sweden now has had 84,279 documented cases, so applying the 25x multiplier, we get a total of 2.1 million cases, or about 21% of the population. (Yes, I made another assumption – that the prevalence to known case ratio is static). OK, keep that 21% in mind for a moment.

I’ve been writing a lot recently about the latent immunity of a large swath of the population. The studies pointing to this are growing. The theory is that that T-Cell response is cross-reactive with other Corona viruses, including the common cold. I cited studies last week. Here is the important one:

https://science.sciencemag.org/content/early/2020/08/04/science.abd3871

A recent paper from Oxford University takes into account the variability in susceptibility to the disease, and calculated a Herd Immunity Threshold of between 10 and 20%!

https://www.medrxiv.org/content/10.1101/2020.07.23.20160762v1.full.pdf

Here is an important quote from the paper: “These findings have profound consequences for the governance of the current pandemic given that some populations may be close to achieving herd immunity despite being under more or less strict social distancing measures.” This is simply stunning.

What does this all mean? Simply put, if we have a significant percentage of the population with some resistance to the disease, the herd immunity threshold is much lower than the long thought 60-70%. Another way of saying this is that with a disease like this, with some level of societal resistance, we don’t need nearly as many cases as previously assumed to reach the turning point. This is what I’ve been seeing in the data, with a ceiling on known active cases (which are a fraction of actual prevalence) at a very low 1/3 of one percent of the population. I’m guessing this is where Sweden is now, having reached the Herd Immunity Threshold.

Let’s look at Sweden’s mortality results. As of today, Sweden has had 5,783 deaths. They are now down to low single digit deaths per day, so this number is incrementing very slowly. If we compare deaths to date with the 15 states I track we see that Sweden comes near the middle of the pack. AZ, NY, NJ, MA, PA, and MI fared worse, and the rest of the states have a better result so far. However, some of these states are still reporting significant daily death counts, while Sweden is not, so I’m thinking that Sweden’s ranking on this graph will even improve over time.

So what do we make of all this? It’s tempting to jump to the conclusion that social restrictions are not effective, but I’m not there yet. I do believe that social distancing, school, and business closures must have an effect, but I bet it’s not nearly as effective as we assume. It’s looking more and more like we can slow down the approach to herd immunity, but we can’t avoid it, hence the set of states that peaked early and low, but are increasing again. It will take years of research and statistical analysis to sort this out, but I think now the burden of proof has shifted to those favoring restrictions.

I do realize I’m treading on controversial territory here, but as always, I continue my pursuit of unraveling the mystery. Feel free to send me your questions about my assumptions, methodology, or modeling in general.

  • Likely date of active case peak (Chalke modeling): July 23
  • Likely date of peak deaths (IHME): April 16 (last revision on August 6)
  • Total Test Results reported today: 777,569 (very high)
  • Total Pending tests reported today: 4,302 (extremely low)
  • National reported case Growth Rate today: 0.81% (record low since the beginning of the Pandemic)

Shane Chalke Interviews

https://www.fredericksburg.com/opinion/editorial-unlock-demographically-not-geographically/article_a62e6e70-dccd-51cf-b7b2-16d77a90fd9c.html

Website

Groom Ventures has agreed to host a website that will archive my daily reports, and supplement with other commentary. John Groom worked at one of my companies back in the day, and is an excellent writer. The website is: www.howmuchrisk.com For those of you that post my daily report on Facebook, let me suggest you link to this site, as the direct Facebook posts don’t seem to copy the graphs.

Daily Analysis

Here is the national picture. We’ve dropped over 100,000 known active cases since the peak of July 23rd. That’s a 23% decline, and puts us back where we were in early July. That leveling you see is mostly driven by two very large states — California and Texas, which are not definitively declining yet (see below).

Look at the daily new cases. We’re looking at a broad pattern of decline since mid-July.

The daily death count is flat for nearly a month. I expect a gradual decline beginning next week. Here is the picture:

We’re still seeing the daily death count much smaller in relation to case count than we experienced in April. As predicted, daily deaths have flattened out over the past week, and I expect them to begin declining in another week.

Here are the daily deaths per 1,000 known active cases. This disease is far less deadly than it was in April, when deaths per active case were 4 – 5 times higher.

On to the states.

Her is Arizona, now down 74% from the peak just 40 days ago. This is wonderful to see. The news is finally talking about Arizona faring better, but you’d never know from the reporting that Arizona has just one fourth the COVID they had last month. This is positive news.

SC is also much improved. SC is now down 56% from the peak. Note that South Carolina double counts cases, as they treat each positive test as a new case (per The COVID Tracking Project).

Here is Florida – another strong recovery story. Interestingly, I noticed Miami flattening first, but Miami is not doing nearly as well as the rest of the state. With one out of every 19 residents documented to have had COVID, I’m surprised Miami isn’t falling fast. Florida is now down 51% from the top.

California has climbed steadily over the past week. As I pointed out in the past, California peaked at only 0.18% of the population, so I believe there is more to come. As always, I need to report that California is one of the states that counts tests rather than people.

Georgia’s recovery is not as pronounced as the other states hit hard in late June, but is looking better lately. Georgia hit a high of 0.25% of the population, so I’m thinking this could be the ceiling, but the pattern is just different enough that I have some skepticism. GA is down 22% from the peak. Note here again, the case numbers are exaggerated. Georgia counts each positive test as a case (according to The COVID Tracking Project).

Texas is looking like Georgia now. Down from the peak, but not definitively in decline. I’m suspicious there could be more to come here. Note that Texas also reports positive tests as cases, so is doing some level of double counting.

NC is down 38% from the peak, but the peak was at a very low level (0.14%). Nonetheless, NC new cases are in decline, so the pattern looks good. If this pattern continues, NC will definitely move to Phase 3 on September 11, if not sooner.

I won’t comment on this again (I know, it gets boring), but that recent bump in VA is a result of a backlog of testing data released on August 7th, and the various tracking sites, including The COVID Tracking Project, pick them up as new cases. Virginia is working to place the cases back on the correct dates on their website, and eventually the Tracking Project will catch up with this, but for now we’ll see this bump – it is NOT indicative of a surge in cases.

Here is the daily death report for NC, flat for 3 weeks now. We’ll start to see this decline soon, as the active case count has fallen fast.

Washington could have peaked, but I remain skeptical, as the high water mark you see here is at just 0.087% of the population. However, that peak is now a month old, so that’s hopeful.

Here are NY and NJ – both relatively steady at small percentages of the population.

Here is Massachusetts, just about through the bubble of new historical cases caused by reporting errors at the very end of July (https://www.wwlp.com/news/state-politics/reported-error-caused-spike-in-massachusetts-covid-19-numbers/).

…And here is Michigan. Looking beautiful until June 10th, then beginning a steady upward drift. Michigan peaked at a low percentage of population (0.089%), so may continue to grow if my theory is correct. It is just one of several states that peaked early and low, and doesn’t seem to be done with COVID yet. Nonetheless, MI has been flat for over 3 weeks now. I have no idea what is likely to happen here.

PA is about where they were 5 weeks ago. I believe PA has more growth to come, as the peak was very low (0.091% of the population).

And finally, here is Colorado. Colorado is one of the states that has had aberrations in their data. I still report it, but I’ve shied away from any conclusions in this state due to the data irregularities. Very small numbers here. Colorado peaked at a very small percentage, so could peak again as well.

So that’s it for today. I’ll report again on Thursday unless something notable happens between now and then.

The numbers are still very small as a percentage of the population. Unless you’re in a high density area, your chances of contracting COVID are very small. However, even though the probability is very small, that doesn’t help if you’re the one catching it. Everyone please continue to be as cautious as you feel necessary.

–Shane Chalke, FSA

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