Does “flattening the curve” really save lives?

… or, realistically, does it just postpone the inevitable?
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How many times have we heard: “Flattening the curve will save lives… maybe millions of them”?

Let’s hit the pause button and review the theoretical basics and what we’ve learned.

This is the conceptual drawing of the “flattening curve”  we’ve had flashed at us a zillion times.

image

Time is on the horizontal axis,; number of deaths(or cases) are on the vertical axis; the high humped curve is the number of deaths (or cases) each day with no mitigation; the shallow curve is is the number of deaths (or cases) each day with with mitigation; and the white dotted line is hospital capacity.

OK, let’s unpack the curve…

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What’s the objective?

Flattening-the-curve strategy was predominantly sold-in as a way of saving lives — from 2 million to under 100,000.

That was a pretty compelling selling proposition.

Only parenthetically was it mentioned that the strategy would keep us from blowing past our hospitals’ capacity to treat the swell of patients.

It’s now evident that staying within hospitals’ capacity was really the primary objective.

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What’s the time frame?

Again, time is on the horizontal axis.

Originally, the mitigation strategy was sold-in as “15 days to slow the spread”.

That was extended by 30 days when flattening wasn’t compellingly evident … and now varies ambiguously state-to state.

The point: Folks were highly supportive when the stay-at-home plan was 2 weeks long … but, support began to wane as the time period was stretched out.

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Was there enough hospital capacity?

Answer: In aggregate (i.e. across the whole country) hospital capacity far exceeded the demand.

Best evidence: many hospitals have laid off medical staff … and some hospitals have shuttered since the strategy put a moratorium on profitable elective surgeries.

But, capacity was stretched to near limits in some metro hot spots, notably NYC.

The Feds were able to quickly respond with supplemental capacity (make-shift hospitals, ventilators, etc.) that was minimally used. indicating that the stay-within-capacity objective was met in the most demanding situations … and over-achieved in the vast majority of locales.

Observation: The healthcare system (with Federal supplements) had capacity to treat more patients .. if the nation had pain-tolerance to accept more cases (and more deaths).

Which gets us to the headlined question…

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Does flattening the curve save lives?

We need another conceptual point:

Since the curves represent the number of deaths per day, the areas under the curves represent the total number of deaths (since the first case).

image

Save for some special situations that we’ll cover later, the areas under the curves stay the same.

Said differently, the total number of deaths doesn’t change … they just get spread out differently.

Under a mitigation strategy, the deaths just get postponed.

That is, unless…

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Are there any death-reducing hopes?

Short answer: maybe.

For example, if ventilators had really been in short supply, stretching demand for them over a longer time period would have provided more ventilators for needy patients … conceivably saving some lives at the margin.

But, that wasn’t the case.

Similarly, stringing out the cases gives medical teams time to move up the “learning curve” and develop finely-honed treatment protocols (high efficacy drugs or procedures) that have life-saving potential.

Missed opportunity: When clustered deaths occurred in the Seattle nursing home, high priority could have (should have) been put on senior care facilities with targeted protocols (testing & procedures) that would have actually saved lives … not just postponed virus-related deaths.

More generally…

Saving lives in large numbers requires a virus-terminating intervention (VTI) the materializes during the the mitigation time period (vertical red line below).

If there is a VTI, the yellow shaded triangle below would represent the number of lives actually saved by flattening the curve..

image

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What kind of virus-terminating interventions?

There are several possibilities:

  • The virus could die off “naturally” … say, if it can’t withstand summer heat.
  • A vaccine could be introduced that potentially stops (not slows) the spread of the virus.
  • Herd immunity develops, reducing the portion of the population that is susceptible to the virus … and cuts the number of infectious virus-carriers, minimizing the contagiousness to the remaining susceptible population.

Of course, none of the above are slam dunks.

There have been some studies indicating that heat, humidity and UV light impede the virus.

While there is a reported stream of vaccines under development, the bare fact is that no vaccines have ever been successful for combating corona-like viruses.

Herd immunity requires that (1) infected patients who survive develop enduring immunity to the virus, and (2) 60% to 80% of the population survive infection and develop the immunity.

You can set your own odds of any of the virus-terminating interventions occurring.

And, keep in mind, without one or more of them, mitigation only saves a few lives at the margins … it mostly just postpones the inevitable.

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If you found this explanation useful, send it to a friend…

2 Responses to “Does “flattening the curve” really save lives?”

  1. WSJ: The data are in … | The Homa Files Says:

    […] For a conceptual derivation of this point, see our post Does “flattening the curve” really save lives? […]

  2. From “flattening the curve” to “learning curves”… | The Homa Files Says:

    […] For details see: Does “flattening the curve” really save lives? […]

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