This is a lesson in how deficient the data and analyses are that health officials have provided to the public on COVID-19.
We tried to answer the most basic questions about where the pandemic is heading in Illinois in light of the torrent of new COVID cases: With case numbers exploding, won’t Illinois very quickly be overwhelmed with infections and herd immunity? How many deaths will result? Can hospitals handle the surge?
We looked for a model or projection that might answer at least some of those questions but found none, so we used official numbers from the State of Illinois and the Center for Disease Control to try to answer for ourselves.
Here is what published, official numbers imply: Seventy percent of Illinoisans – nearly 8.9 million people – will be infected with COVID by early December. Herd immunity, whether we like it or not, will therefore be reality by then.
Those conclusions are faulty and at odds with policy and prevailing understanding, even though they are based on official numbers. But how far off are they? We can’t say. It’s an illustration of why health officials must give us better numbers and provide models and projections consistent with those numbers.
Official numbers indeed seem to say, on the surface, that 70% percent of Illinoisans are headed for infection by early December. Here is the short version of the math behind the projection, which we did in more detail than shown here:
New “cases” – reported, actual infections – are now growing at a remarkable rate, as you can see from this chart:
At the current growth rate, Illinois would reach 890,000 confirmed cases around December 13.
But – and this is key – every confirmed case means there are 10 actual cases, which is a widely published number from the CDC. In fact, the the CDC recently increased that number to 11, but we used 10 to be conservative.
So, the cumulative number of Illinoisans infected will reach 8.9 million around December 13.
That 8.9 million is about 70% of Illinois’ population, which is widely seen as the point at which herd immunity is achieved. Many experts, however, put that percentage lower, some as low as 40%, which would mean Illinois would be well past herd immunity by early December.
“Herd immunity” is the term given to the level of infections at which the virus begins to recede because so much of the population has been infected and is therefore immune. Put simply, it’s the point at which the virus has no place to go so it begins to disappear. It’s why most viruses ultimately disappear.
So, if official numbers were correct and adequate, our projection would mean that the pandemic would start resolving itself in less than two months, even without a vaccine.
But that’s not right, for a number of reasons. To get it right, we would need more information. We would also need experts doing a more complex model that we probably couldn’t do – experts who aren’t politicized. And to get that, we would need the media to be pushing for it and asking the right questions.
Here are just a few reasons why the projection above is faulty.
First, that ratio of unreported cases to reported cases, which the CDC now says is 11, is not fixed. It will decline as more people get infected. In other words, we will hit a curve as higher immunity levels kick in, so our straight-line projection isn’t realistic. But we can find no tool or formula that adjusts that number over time. Building it into a projection would be better left to an expert.
Second, scientists don’t fully agree about immunity for those who were previously infected. Most seem to agree that a high degree of immunity lasts for at least four months after recovery, but that’s not certain.
Third, the effects from a new vaccine should be reflected in any model or projection. Those effects should begin kicking in by January. Experts have long anticipated the new vaccine announcement and there should already be projections that reflect its effects, but where are they?
We used “official” numbers even though we are well aware of other underlying questions about those numbers. Those questions include whether false positive numbers are being reported as cases, and whether tests are overly sensitive thereby recording harmless virus remnants as infections. Those issues, too, could change the projection.
What about the other key questions? With no good way to project future infection numbers, and with no good projection from health authorities, those other questions are unanswerable as well.
Specifically, how many will die because of the new surge? That’s what makes herd immunity controversial – the number of deaths required to get there. We can’t answer without a good projection on infections, and nobody has provided one. The number of deaths, however, almost certainly will be lower than you would think based on past fatality rates. That’s because infections are increasingly concentrated in younger people, who face virtually no fatality risk, and because treatment has improved significantly.
And what about hospital overload? Again, we can’t speculate without a good projection of infections. Anecdotally, we are also hearing from hospital personnel that hospital stays for COVID-19 are now shorter than before. Perhaps that, too, should be reflected in a meaningful projection.
Why hasn’t the public been provided with a credible projection or model?
In the case of Illinois, maybe it would be embarrassed to try. The last time Illinois officials talked about new models they turned out to be wrong before they were even released. And the IHME model from the University of Washington, which was earlier the most cited in the nation and among those Illinois used used, turned out to be consistently and badly wrong.
The bottom line is that if you want understand where the virus is heading in light of the new surge you will be frustrated. Neither state or federal officials have told you much or given you the numbers to figure it out for yourself.
And the media aren’t asking.
Special thanks to a particularly smart Wirepoints reader who has been tracking in detail all the numbers relevant to the projection discussed above. He sent his calculations, which we confirmed. He shares our frustration about lack of the critical information and hopes that both public health officials and the scientific community will start providing more meaningful numbers and analyses.