According to the IHME statistical model’s projections, the US reached its pinnacle of daily covid deaths two days ago, on Good Friday. Though the subsequent mortality dip in the curve isn’t expected to be as precipitous as was the ascent, the model still projects that the daily body count will drop to single digits by early June.
During the upswing, actual deaths have come close to the projected numbers. What about the downstroke? It’s too soon to tell, since we’re still only a day or two past the presumed apex.
What about other countries that reached the top of the death curve earlier in the month — have their rates dropped? Italy for example — its early sharp death spike reached a peak of 969 on March 27. The IHME model projected that, due mostly to widespread social isolation, the Italian death rate would decline markedly, down to 335 on April 10 and 281 on April 11. According to Worldometer’s data, however, Italy’s actual death counts the past two days were 570 and 619 — nearly twice the numbers projected by the model. While the death rate did drop during the first week after the peak, it’s now plateaued for the subsequent week.
How about Spain, its situation similar to Italy’s? Spain’s daily deaths topped out at 961 on April 2. For April 10 and 11, the IHME model projected Spanish deaths at 304 and 262; Worldometer reports that actual deaths were 634 and 525 — again, twice the projected numbers.
In order for the death rates to drop, the contagion rate has to drop. COVID-19 is a highly contagious disease: under pre-isolationist societal conditions the average infected person was infecting 2.4 others. Slowing the infection rate keeps the healthcare system from being overwhelmed, but it doesn’t necessarily reduce the total number of people who will eventually contract the disease and die from it. In order actually to bring new infections from this first wave to a halt, the interpersonal contagion rate has to drop below 1.0. If that threshold is achieved and new infections drop to small numbers, then when a new outbreak of the disease shows up it becomes feasible to deploy more precisely targeted interventions of social isolation and contact tracing, keeping the viral spread from building momentum and spreading out of control.
But what if current social isolation measures are able to reduce the contagion rate to some level below 2.4, but not enough to drop below the 1.0 threshold required for the wave to extinguish itself? The infection rate will slow, and so will the death rate, but gradually, and inexorably, the viral wave will sweep its way across the entire population.
It’s likely that early next week, based on three days’ worth of new data, IHME will revise its mortality estimates upward for Italy and Spain. It’ll take at least another two weeks for the post-apex body count trend to make itself evident. Conceivably the models will have proven overly optimistic, and the first wave will be the only wave, which won’t wash out until it’s passed over the entire population.
Lately the daily count of newly confirmed diagnoses has been holding steady at around 34K per day. Everyone agrees that the real numbers are much higher, maybe ten times as high. Let’s say there are 5 million active cases in the US with 340 thousand new cases added daily. Even if the nation could mobilize massively on short notice — which clearly it cannot — there’s no way that any sort of effective individual isolation and contact tracing could be implemented mid-wave, bringing the numbers down. The wave will have to run its course: maybe 200 million people infected, maybe 1 million dead.
If current levels of social isolation can’t stop the wave, then the policy question will come down to two options: either keep the wave moving slowly, by maintaining continued levels of social isolation; or let it speed up, by relaxing the constraints and returning to “normal.” Maybe issue warnings to the old and infirm who are the most likely to die if infected: for your own safety, continue sheltering at home. Implement infrared fever-detection protocols at workplaces, schools, and nursing homes to facilitate targeted isolation of individual cases that could slow group contagion. Roll out new treatments that offer some relief of symptoms, possibly reducing severity and bringing down death rates. Get that vaccine invented, tested, manufactured, and rolled out.