By: Ted Dabrowski and John Klingner
Lost in the attention over Illinois’ massive spike in COVID-19 cases is the collapse in the virus’ case fatality rate, or CFR. At the height of the crisis in June, almost 5 percent of Illinois’ recorded COVID cases resulted in deaths. But as recorded cases have risen significantly over the past three months and deaths have not, the fatality rate from August through today has dropped to just 0.9 percent.*
The latest COVID data is quickly revealing how less fatal the coronavirus really is, and that has major implications for lockdown policies and, in particular, for school shutdowns.
That drop in the case fatality rate reflects a dramatic increase in the number of COVID tests being performed, a significant increase in rates of infection among younger Illinoisans and reportedly better overall treatment of the virus.
Illinois’ CFR is gradually dropping toward what the Center for Disease Control estimates is the virus’ true infection fatality rate (IFR), about 0.65 percent. In contrast to the case fatality rate, the IFR includes estimates of all infections, including asymptomatic cases, not just reported cases.
It’s important to note that the 0.9 percent case fatality rate reported above is an average across all age groups and it’s still heavily influenced upward by the high death rate for those 80 and older. The actual CFR for the younger age brackets is dramatically lower. We break out those numbers in a following section.
Illinois cases, hospitalizations and deaths
Daily reported cases in Illinois, based on the 7-day rolling average, have jumped to about 12,000 a day. That’s five times higher than when the state’s cases last peaked on May 7th.
But while cases have quintupled, hospitalizations are still flat when compared to their first peak in May. We’ll have to keep an eye on where hospitalizations go, but what the data shows is the tens of thousands of new cases in Illinois over the past month haven’t required the same levels of medical care as earlier in the crisis.
That doesn’t mean hospital capacity issues won’t be a problem, but overall, the spike in cases hasn’t been followed by a corresponding massive increase in hospitalizations.
The breakdown in correlation between cases and deaths is even more pronounced. Daily deaths, based on a 7-day rolling average, are still 45% percent lower compared to Illinois’ original peak in May. Illinoisans should also keep an eye on deaths, but just like with hospitalizations, the data shows that a dramatic increase in cases hasn’t translated directly into far more fatalities.
Illinois’ collapsing case fatality rate
As mentioned earlier, the state’s case fatality rate was at a frightening 4.9 percent at its height in June.
Illinois’ high CFR has been driven steadily downward since then as the daily increase in COVID-19 cases have far outpaced the growth in deaths. Illinois’ overall case fatality rate has fallen to just over 2 percent when the total number of deaths since March (10,196) is divided by all of Illinois’ recorded cases (487,827), as of Nov. 8.
The collapse in the fatality rate is even more visible when you look at the cases and deaths of the last three months in isolation. Since August 1, there have been 2,701 deaths on 307,351 confirmed cases, resulting in a case fatality rate of just 0.9 percent.
The fall in the CFR is driven largely by two factors, in addition to better treatments. One is the significant increase in testing, which has led to more cases than otherwise would have been recorded. The state is now performing 80,000 to 100,000 tests daily, compared to just around 20,000 during the May/June peak.
The second is that younger Illinoisans make up far more of the cases today. It’s hard to see in the graphics provided by the IDPH, but they show that the 20- to 49-age demographic has dominated new cases over the past several months. That’s in contrast to the start of the crisis, when most of the cases were the elderly and the infirm who ended up hospitalized.
The below table breaks out the state’s CFR by age bracket.
Illinois’ overall CFR data since the inception of the virus shows that the fatality rate is now just over 2 percent. However, that’s heavily influenced by the 22 percent CFR for those 80 and older. The fatality rate for those under 20 is just 0.012 percent.
Those numbers drop significantly, however, when you look at the deaths and cases of just the past three months. The CFR for those 80 and older has fallen to 13.3 percent. While still deadly for too many, that’s a significant improvement in the CFR of more than 30 percent during the May/June peak.
On the other end of the spectrum, the CFR for school-aged children has collapsed even further to 0.006 percent.
As more and more cases are captured by testing, the CFR figures continue to move toward the CDC’s estimated infection fatality rates, as shown below.
The plummeting case fatality rate has major policy implications for the state’s COVID-fighting tactics – specifically for school district shutdowns and the state’s lockdown policies.
School districts, specifically, have all the data they need to successfully return to more robust levels of in-class learning – even amid the recent rise in cases. The latest case fatality numbers help confirm the extremely low fatality numbers shared by the young and middle-aged. New transmission research continues to show that schools are not the superspreaders they were once feared to be. And improved testing methods, such as New Trier School District’s new saliva screening adds even better protocols to districts’ safety procedures.
And more broadly, the latest CFRs mean the use of broad economic lockdowns to control COVID-19’s spread – leading to deaths of despair – may be doing more harm than good. The numbers show that Illinois’ fatalities are still concentrated almost entirely among the elderly and medically vulnerable.
The state’s mitigation strategy should reflect that by focusing protection on those demographics, as opposed to shutting down the state.
*Another measure of the case fatality rate assumes deaths lag cases by approximately two weeks. The below graphic captures the CFRs assuming that lag. In the case of the overall CFR from March to November, the CFR rises to 2.7 percent from 2.1 percent (no lag).
In terms of cases of deaths since August, the CFR rises to 1.4 percent from 0.9 percent (no lag).
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