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More Coronavirus Information and Perspective

By March 29, 2020Commentary

What about a Vaccine or Cures?

One reasonable explanation for actions to mitigate the spread of the coronvirus 19 strain is that it buys time to develop a vaccine or find existing or new drugs that may help control the illness it could cause.  I would exercise caution in regard to those possibilities.  Partly my caution comes from the experience with influenza viruses.  We have vaccines and they provide a fair degree of protection from getting the flu, but you only have to look at the annual rates of illness, hospitalizations and deaths to realize that it is still a serious health problem.  Influenza viruses are relatively unstable, that is they have frequent sequence changes that make creating a universal vaccine difficult.  And this is why we have to get new flu vaccine immunizations every year.

From what I have read, scientists so far believe that coronaviruses in general, and this strain, as well, are actually fairly stable–they have low rates of mutations.   This would be good news, as it would imply that a vaccine might confer longer-lasting protection, which could potentially be given less frequently.  The factor that weighs against this is what I understand to be the relatively short lifetime of human antibodies.  Coronavirus antibodies appear to disappear in the course of a couple of years.  I am not sure why this would be so, and perhaps a vaccine would prompt development of antibodies which last longer.  In any event, realistically we want to ensure that a vaccine works and is safe and that requires fairly large and lengthy trials.  I am sure development and testing will be accelerated, but I think 9 months would be quite quick and at least a year more realistic.

There are several existing drugs that may be effective in combatting the nastier consequences of a coronavirus illness, but those too should ultimately be subjected to some testing to verify that they will work for large segments of the population. So far the evidence is largely anecdotal.  New drugs specific to coronavirus are being worked on, including some antibody approaches, but again, let’s be realistic, it will be a few months, at a minimum, before we know if these are ready for prime time.  So again, I would be cautious in assuming that a vaccine or a drug is going to solve this problem.  The more conservative approach would be to assume that this new coronavirus will be with us for an extended period, likely indefinitely, and that we will be battling it every year, just as we do with the flu.

Do Extreme Mitigation Measures Work?

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.

Protecting Medical Resources Against a Surge in Demand?

We have extensive, but not unlimited, health resources in the United States.  There has been a substantial push in the last decade in particular, to reduce hospital use and that has inevitably resulted in a reduction in the number of hospitals and hospital beds.  Seriously ill coronavirus patients often need hospitalization, and even time in an intensive care unit, which may often include mechanical ventilation to aid in breathing.  The United States actually has the highest number of ICU beds per capita in the world, largely because we tend to utilize much more aggressive end of life care than other countries and we have higher rates of significant trauma cases from events like car accidents and shootings.  We have 100,000 beds in ICUs.  That is a lot of ICU beds.  Obviously some of those beds are being used for patients treated for conditions other than coronavirus illness.  But the bigger problem is that the beds are scattered across the country and aren’t necessarily where there may be large numbers of coronavirus cases.

Right now, we don’t appear to have an actual shortage of ICU beds or ventilators.  Ventilators are obviously easier to move from one location to another and a larger supply can be produced somewhat quickly.  It is not possible to move an entire ICU unit.  It is possible to convert hospital units to additional ICU capacity, but that takes a fair amount of work.  And it is possible to be creative about using other methods of adding hospital beds–using hospital ships and repurposing large public building to be temporary hospitals, for example.  Having sufficient qualified medical personnel is also important.  Health workers have an enhanced likelihood of getting coronavirus infection, due to proximity to already infected patients.  Even if they become sick, the workers would need to quarantine to avoid becoming an infection source themselves. So being short-staffed is possible.  We can add medical personnel for coronavirus treatment by using people who otherwise would be working in less urgent departments and by inducing retired personnel to come back.

In general, I have a fairly good level of confidence that the system will have sufficient capacity to ensure appropriate treatment for patients, but it is a reason to engage in strong mitigation measures.  No one wants to see any patient die or have a bad outcome because adequate health resources were not available.

More Thoughts on Death Rates

Obviously the worst effect from coronavirus is death.  The per capita death rate is very low in the United States at this point, but will grow as additional deaths occur.  But there is a need to be careful in assuming that the reported number of deaths attributed to coronavirus is accurate at this point.  Currently, deaths are attributed to coronavirus if that reason is listed on a death certificate or from other reporting methods.  But it is likely there is over-attribution.  A study in Italy, which has reported very high death numbers, suggests some of these issues.  (Italy Issues)  Although not like Italy, some of the same issues may be present in attribution of deaths in the United States to coronavirus.

At some point epidemiologists will do a retrospective study comparing death certificates to actual medical records and the number of deaths attributed to coronavirus will almost certainly be reduced. At some point also, we will be able to look at the underlying death rate trend in an extended period before the epidemic began and compare it with the trend during the epidemic. That will be one method to estimate deaths due to coronavirus.  The issue of pre-existing illness and nosocomial (acquired in a health care facility) infections is also of interest in understanding what deaths were caused by coronavirus.

There are also algorithms available that are fairly good at predicting mortality for an individual in the next six months or a year. These algorithms are used by hospitals and others to aid in managing care. So it will be possible to take the population that died and assess the likelihood that these persons would have died in any event in 6 months or a year. Should all those deaths be attributed to coronavirus? Almost certainly not.

Infections acquired while in a health care facility are also worthy of consideration.  These patients went into the facility for a reason other than coronavirus and contracted the virus and/or became infected while there.  This is very likely occurring with some regularity.  In fact, obtaining infections while in a hospital is such a generally significant issue that Medicare has a special program punishing hospitals for excessive rates of hospital-acquired infections.  So if the patient gets coronavirus in a hospital and ends up dying from the infection, would the same death have occurred–would the patient have contracted the disease in the community?  It is a coronavirus death, assuming it is not also affected by the pre-existing illness issue, but seems to be in a different category.

Just items to be aware of in looking at death rates.  In retrospect they are likely to be lower than they appear at this point.

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