Do Extreme Mitigation Measures Limit Ultimate Infections or Deaths

By March 27, 2020 Commentary

There are various rationales advanced for the extreme mitigation measures we are experiencing today.  One is that it will prevent disease and deaths.  Another is that it protects scarce health resources that might be overwhelmed by a surge in cases needing advanced treatment.  I will deal with that question in a separate post.  In regard to the first, it should be clearly understood that the purpose of the mitigation efforts is not to prevent infections or deaths, but merely to delay them.  All the talk of flattening the curve should be understood for what it means, the area under the curve–the number of infections and deaths–stays the same, it is just spread out over a longer period of time.

So if a Governor, say of an upper-Midwestern state, claims that there will be a 50% infection rate and 74,000 people will die if he doesn’t lockdown the state, he isn’t saying those infections and deaths won’t occur if he does lockdown the state, just that it will take longer to experience them.  There is one circumstance in which some excess deaths in or more properly, over those numbers might be prevented.  If the number of serious illnesses was sufficient to overwhelm treatment facilities, some people might die who otherwise would not.  But if he really believes the infection rate is 50% and all the other rates fall in line according to his model, there will be 74,000 deaths, sooner or later.

Now, in fairness, and what he doesn’t say, is even non-extreme mitigation measures will flatten the curve.  A good question is: how much does any individual mitigation action contribute to the spreading out of infection and death over time.  I strongly suspect that the lockdowns are at best incremental to what I will call hygiene, social distancing, quarantine and protection of vulnerable population measures.  In other words, I think you get a lot of your deferral of a surge in cases from those actions alone.  Which is why I think the cost of that incremental benefit you get from extreme measures is simply too high to be borne.

Another reason, at least at this time of year, to attempt to defer infections, is that coronavirus appears highly seasonal.  Go back to that link to the medical textbook in the post on what is a coronavirus.  Look at the chart on the seasonal pattern of coronavirus infections.  It is not unreasonable to think that when we make it to significantly warmer and more humid weather, the infection rate will fall, presumably because the virus doesn’t survive as well in those conditions, people open up and ventilate their houses, etc.  This effect can be seen also in the distribution of infections around the world.  Countries in temperate zones seem to be experiencing higher infection rates than those in tropical zones.  We don’t know for sure that this variant will follow the typical pattern, but it seems more likely than not that it will.  But again, the less extreme mitigation measures will get us most of the way there.

And no one should believe that we are making the virus go away.  It is here.  It has probably been here longer than we realize.  Before China came clean, there likely were a number of cases of infection and illness in the United States that were not recognized as being coronavirus related.  And it isn’t going away.  There is no measure that wipes it out magically.  So we have to adapt to it, like we have to influenza viruses.  People who are infected build up immunity.  We can help that process with vaccines.  And when enough people have immunity, it becomes hard for the virus to be widely transmitted; the chain of transmission is too easily broken.  This process is sometimes referred to as herd immunity.  The longer we defer the infection cycle, the longer it takes for a significant part of the population to develop immunity.  And the longer we think we need to put more moderate and more extreme mitigation measures in place.

I think it is likely the infection incidence will naturally fall in the coming weeks, due to seasonal factors.  But our deferral of infection spread, coupled with any seasonal fall in infection rates, will likely mean that the resurgence next fall and winter will be more severe than it would be if we endured more infections now.

And one final point, which I keep coming back to, why is the infection rate so low.  It is a good thing, but understanding why could help us manage our relationship with the virus more effectively.

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