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.

-Mark Glennon, Ted Dabrowski and John Klingner

Notify of
Oldest Most Voted
Inline Feedbacks
View all comments
23 days ago

Thank you for bringing up such topics. In fact, what is happening in the world now is very frightening and I partially understand all those who are trying to downplay the results. Because people panic very easily, and there are not enough places in hospitals to cope with such a flow of sick people. After all, the number continues to grow every day and no measures help get rid of the infection. Therefore, on the one hand, people need truthful information so that they do not think that this is some kind of joke. So that everyone understands that this… Read more »

24 days ago

Your whole calculation is based on saying that each reported case represents 10 actual cases. But in fact, this estimate is very rough and disputed. If this is wrong, and the people doing this estimate say themselves it may be quite wrong, your whole argument falls apart. Anyway, it isn’t clear how long immunity lasts. We do know that for some people it has only lasted three or four months, and they got infected again. So, even if herd immunity was reached for a short period of time, there could be another wave in a few months after herd immunity… Read more »

23 days ago
Reply to  Doly

Do you know how vaccines work? They introduce attenuated virus to a body, then that body develops immediate antibody response as well as T-cell response (later recognition of that particular antigen and an ability to produce antibodies in response at that time). Your argument indicates your position is that a solution can never be achieved because vaccines (the equivalent of herd immunity) can never be effective for longer than 4 months. Therefore, what do you suggest? If you claim to value human life, you should insist that hospitals shut down, lest doctors and nurses be made to die. Amazon warehouse… Read more »

Downstate cynic.
24 days ago

total tests and total positives are meaningless numbers. today the major goal is to reduce or shorten hospitalizations. To predict near future health care burden we should be tracking the positive rate or regional absolute numbers by region compared to available beds for people over 50 or 60 yrs of age. This would tell us about the population at risk of using hospital resources. Including younger people in the count really overstates the risk of swamping the hospitals. And we should then focus mitigation on that population. We are seeing steady increase in those with respiratory symptoms so the PCR… Read more »

24 days ago

There is immunity through T cells. The narrative that there is no long term immunity is BS media scare tactics.

25 days ago

Lard boy and the Drama doctor are the ones reporting so Question everything they push out there.

Paul Brancky
25 days ago

Thanks for the pushing forward the discussion in a thoughtful manner.

I agree that there are people with the skill sets and tools to provide the insights our public officials need to make more informed decisions. We can and must do better.

You are on the right track. Thank you.

25 days ago

So im watching the local new last night and OMG!-13% covid cases in Illinois!-then they explain that its 13% of those that are tested,thats roughly 1 out of 7 people who “are tested”- not 13% of the population-seems to me that it should be a lot higher percentage ofCV those that are tested.Why are these sheep getting tested unless u are sick.I have a hangnail,i better get a covid test.Does anyone in Illinois do any independent thinking for themselves or do most people just listen to what JB bloviates abour? Yes mr pritzker,cuz you said so I ll close down… Read more »

Last edited 25 days ago by David
Joey Zamboni
25 days ago

The first mistake is relying on the *experts*…

Many have been consistently proven wrong…

Next look at our so called leaders…

They casually flaunt their own rules & edicts they have imposed upon us, the unwashed masses…

We have been under more restrictions, & yet the virus is still allegedly spreading…?


40 cycles of testing is why…

25 days ago

It’s ALWAYS been more about a political narrative than public health. The casual observer has noticed now that Joe Biden is the presumptive president-elect, the discussion of deaths has stopped. In fact, MSLSD took down their Covid death counter Sunday.

There is no interest in the truth with Democrats it seems – just a political narrative that favors their near term interests. If truth and transparency were important, JB Pritzker would disclose how much he and his family have profited from the record amount of testing.