An updated big picture on the COVID-19 epidemic

By Kevin Roche

Could be a number of new readers, thanks to Phil Kerpen on Twitter, who recommended that people follow me, and another column in the Strib.  That column should have been written by a physician and I don’t know why someone hasn’t stepped up to provide better education to the public and better expectations.  As always, when people don’t like the information or commentary, they go after your “credentials” instead of attempting to demonstrate why you might be wrong.  I believe it was Martin Luther King who encouraged us to strive to judge a person not “by the color of their skin but by the content of their character”  My addendum would be let’s judge people by the quality of their ideas and analysis, not the string of letters they have behind their name.

photo by Cate Bligh

But for new readers, let me just say that my background includes 50 years of experience in health care, including working as a nurse’s aide and running multi-hundred million dollar businesses.  I understand health care data and analytics.  I have been reading health research for 40 years and writing a blog on health care research and policy for over ten years.  So I know how to read and understand and critique data sets and research.  With the help of Dave Dixon and others, we have been able to provide more insight into the course of the epidemic in Minnesota and nationally and give people easy to understand graphical representations of that course.  Among the areas I have become familiar with in the course of my career are epidemiology and immunology.  So when the epidemic began and I saw the horrific public response, I felt well prepared to try to provide people with information that would help keep them balanced and rational.  And yes, some of my commentary is biting, even harsh, but also I believe adds a little humor to a dark situation.  Hopefully the blog has met that objective.  And once again, let me express the deepest possible appreciation for readers, every one of you, including those who often disagree with me.

Now, as I have said repeatedly in the last couple of weeks, I thought we would be done by now, and I wouldn’t be writing much on this topic.  But the coronamonomania terrorists seem to have other ideas.  So once again, let me attempt to provide a big picture understanding of this epidemic and the policy responses to it.  For those of you who want more detail, I would refer you again to my epidemic presentation which is up on YouTube, a little dated but the basics are accurate.  (Video Link)

Coronaviruses are very common; we all are exposed to them regularly; what are referred to as seasonal coronaviruses are one of the usual sources of colds.  The good news about this is that most of us, especially children, have some adaptive immune response to attempted coronavirus infections.  Twice before CV-19 in recent decades, coronavirus strains that were more deadly had jumped from an animal host to humans, but those contagions were relatively limited.  It will be hard to ever definitively determine how CV-19 arose, the Chinese have no incentive to be and will not be forthcoming in that regard.  At this point, it appears more likely than not to me that the Chinese took a coronavirus which was already well on its way to becoming more transmissible in humans, modified it further and experienced a lab escape.  Once the virus was out, whether it arose naturally or by lab modification, given global travel patterns and other factors, an epidemic was a foregone conclusion.  Early transparency by the Chinese would likely have facilitated a faster and more effective response, but given what we now know about CV-19, it was going to spread, and is still spreading, almost regardless of efforts to suppress it.

CV-19 is a serious public health threat.  No one should minimize that. It can and has caused a lot of very serious illness and deaths among people it has infected. But we should also understand that it is not the bubonic plague and that the response to the epidemic should be measured by the actual threat. Understanding some basics helps to shape a reasonable response.

I always caution that it is important to think carefully about the meaning of even basic terms like “infected” and “infectious”.  An infected person is one who has been exposed to the virus, inhaled (in almost all cases) it, and the virus has gained entry into cells and begun replicating and releasing new virus particles from those cells.  People can be exposed, but not infected.  They can inhale the virus, but their immune system may immediately disable or kill it, or even something as basic as a sneeze may immediately expel it.  A person is infectious when they are infected and the new virus particles their cells are creating make their way into the respiratory tract and are expelled.  Those virus particles can then be a source of infection for other persons.  The number of infectious persons is to me a critical measure by which to follow the course of an epidemic.  These are the people who keep the epidemic alive.  When their number is growing, cases are going to grow; when their number shrinks, the epidemic will decline.  So I regularly post charts of active cases in Minnesota, the people who are actually infectious.

Respiratory viruses obviously largely enter the body through the mouth and nose, and then attempt to proceed to the lungs and other organs and tissue.  A virus has only one real goal:  replication.  They use receptors to gain entry to cells in the nasal passages and more importantly, in the lungs.  Once inside a cell, the virus hijacks the protein-making machinery of the cell to make copies of the virus, which can be done in astounding numbers.  These new virus particles then exit the cell and seek additional cells to infect.  You can imagine how quickly a person can have an overwhelming load of virus.  Some of these virus particles float more freely in the respiratory tract and are expelled into the air, where if they survive long enough, they can be inhaled by another person and start the cycle all over again.

The disease is caused by the malfunctioning of all these infected cells, which are unable to carry on their normal work, and importantly, by our immune system’s reaction to the infection.  The immune system wants to stop the infection, kill the virus or disable it, but in the course of those efforts will kill body cells and otherwise cause release of chemicals which can further damage bodily tissues and functioning.  Most severe CV-19 disease actually is caused by an immune system over-reaction.  Early on a lot of mechanical ventilation was done to try to treat the disease.  Mechanical ventilation is extremely dangerous for a number of reasons, and fortunately physicians soon abandoned it for many patients, but it caused a lot of early deaths.  Recommended treatment patterns have improved greatly and limited the burden of illness.  People who are infected develop an adaptive immunity, described more below, which will limit their ability to be infected again, and provide substantial protection against serious disease even if they do get re-infected.  Re-infection rates appear to be very low.

At a macro level, an epidemic obviously occurs when a pathogen is being spread substantially in a population.  There are still not fully understood basic aspects of this epidemic.  We don’t know, for example, how many virus particles are typically sufficient to infect someone.  Surface transmission appears to be limited.  Airborne transmission is the primary mechanism for spread, but airborne particles range greatly in size and survival time in the air.  We still don’t have a very good picture of exactly how most transmission occurs–is it through larger droplets, or is a substantial amount via small aerosols that remain aloft for very extended times.

Why do some people get infected when exposed, but not many others?  It is very clear that there is enormous variation in susceptibility to infection and infectiousness.  One of the greatest failures of the modeling was not incorporating this variation.  Why does it exist?  The most obvious answer is immune system variability.  Some people have strong innate immune systems, which have a generalized response to pathogens.  Some appear to have a form of adaptive immunity stemming from seasonal coronavirus infections and that immunity limits their ability to be infected by CV-19.   This immune system variability has an interplay with other factors like age and general health status.  The elderly, especially the frail elderly in nursing homes, have greatly weakened immune systems and are susceptible to any disease.  People who are obese or who have other serious health conditions tend to have weaker immune systems.  So as you might expect they are much more likely to get infected and to suffer serious illness and death.  And they are more likely to have high viral loads which make them more infectious.  And we see a pattern in this epidemic where a relatively few people with very high viral loads account for the great majority of transmission to other people.  And the much higher susceptibility in the frail elderly and those in poor health leads to exactly what we see as the age structure of the epidemic, serious illness and deaths are concentrated in those groups.

So the course of an epidemic as measured by cases, hospitalizations or deaths, is shaped by many factors, including the variation in susceptibility and immune system robustness described above.  Other factors which clearly play a role are population age structure, population density, population health status, obesity levels, and access to health resources.  Another notable feature of this epidemic, as with many respiratory viruses, is the presence of waves which tend to vary by geography and season.  When you see these patterns you have to suspect meteorological factors, such as temperature, hours of and intensity of sunlight, humidity, even wind speed and particulate pollution levels. Those factors could operate on the virus itself, which is quickly disabled in sunlight, on the human hosts–time indoors, dryness of the upper respiratory tract, vitamin D levels, etc., or on the act of transmission–do aerosols survive long in warm or cool air or in dry or wet air?  Although not well formulized, there clearly appears to be some seasonal, geographic pattern, which now that we have year-over-year comparisions, seems to persist.  For example the southern and southwestern US states’ case surge is occurring this year at pretty much the same time it did last year.

An epidemic generally ends when enough people have been infected to develop adaptive immunity.  Adaptive immunity involves the body’s ability to recognize the chemical sequence of parts of the virus and develop what are referred to as B and T memory cells that will identify the pathogen if there is a future exposure.  These immune cells are then able to signal and marshal a response that either prevents or significantly limits infection.  Adaptive immunity can be created by infection or by vaccination.  Vaccination presents the body with sequences which it will recognize as likely pathogenic and then develop that memory response to.  It appears based on the research that actual infection creates an immune response at least as strong and durable as that created by vaccination.  When the proportion of people with some form of adaptive immunity gets high enough, the virus obviously has fewer and fewer opportunities to infect vulnerable people and keep that cycle of replication and infection going.  I think it unlikely that we can eliminate exposure and infection, but it will recede to a background level.

As I note above, features of this epidemic include extreme bifurcation in age structure–almost all the deaths are clustered in the very old, and the young have very, very few.  Another noteworthy feature is what I call front-loading, which can give a misleading picture of the burden of illness impact of the virus.  The virus doesn’t randomly sample a population.  Infections early on are clustered in the most susceptible and most vulnerable to serious illness.  One explanation for the wave appearance of the epidemic may be that because a few people are particularly susceptible and also particularly infectious, those people tend to get infected early, spread a lot early, but when many of them have been infected, there are fewer for the virus to reach, and the wave begins to rapidly recede.

Finally, mutations.  Every respiratory virus is numbered in the trillions or even more.  Every replication event is an opportunity for a change in the basic chemical sequence of the viral genome.  Replication involves copying that genome accurately and evolution actually favors allowing errors, sort of way of experimenting to see if a change creates advantages in survival.  The same thing happens in evolution of any living creature, including humans.  So at any given time, millions and billions of replication events are occurring, as are mutations or changes in the original genetic sequence.  Some of the changes will inevitably confer some advantage, and that advantage will allow greater presence of the new strain.  We have seen this continually with CV-19.  But despite early panic about the effect of several new strains, including now the Delta one, over time it becomes clear that they are not more dangerous and usually not even that much more transmissible.

The public policy response to the epidemic alarmed me from the start and as I noted above, is what prompted my writing about it and beginning to summarize data and research for readers.  It is literally unprecedented to shut down businesses and schools and tell people to stay home in the way that we did.  We have had some very serious flu epidemics and we never engaged in these suppression activities.  Not only were these largely futile, but they obviously have inflicted tremendous social, health and economic damage on populations.  These measures were adopted largely out of panic, hysteria and a herd mentality among our political leaders and so-called public health experts.  The countries, such as Sweden, and the states, such as Florida, that adopted a more rational and balanced approach have incurred no greater toll from the epidemic, and in many cases a lesser toll, than those who went full suppression.

I coined the term coronamonomania to describe this absurd fixation on the notion that you even could suppress a respiratory virus in a large, densely populated, developed nation.  Public health officials should be concerned about the health of the entirety of the population, and political leaders should be concerned about the general welfare of everyone in the country.  And they should recognize the limits and failures of various attempts to suppress spread and find alternatives when those are not working.  Instead in the US alone we have seen tens of thousands of deaths attributable not to the virus, but to the suppression efforts which deterred people from seeking needed health care, from isolation of the elderly, especially those with Alzheimers, and from increased drug and alcohol abuse.  This health toll will continue long after the epidemic recedes.  Study after study shows that we are ruining the lives of a generation of children; serious mental health issues are up substantially and suicides increasing as we deprive children of meaning social and educational experiences.  A recent McKinsey study re-emphasized what many other studies have found, the loss of education among children creates lasting harm to their economic and social well-being, and this is especially pronounced among minorities and children in low-income households.  And we have created unprecedented economic turmoil.

And these suppression efforts didn’t work.  They didn’t work in part because they were based on horrible data and modeling.  Using completely unreliable data from China, modelers, first in the UK and then here in the US, painted a picture of a virus running completely amok and killing tens of millions of people.  The modelers ignored obvious early signs that the virus was primarily dangerous to the frail elderly and those with serious pre-existing health conditions and that there was wide variation in susceptibility to infection and infectiousness. They said their models showed that these extreme lockdowns would stop the epidemic.   So politicians went into panic and cover-my-ass mode.  The terror has been sustained by over-attribution of hospitalizations and deaths to CV-19, using unprecendented notions of if you have any presence of the virus, regardless of lack of symptoms, your hospitalization or death must have been caused by the virus.  And the measures made no difference, we see the same classic epidemic curves everywhere.

From the very start, I have tried to encourage a realistic assessment of the situation.  This is a wide-spread, highly transmissible virus that cannot be expunged.  It will be here, we have to adapt.  We can do so with vaccines and effective treatments.  We are fortunate that unlike flu, it does not seem to inflict serious illness on children and younger adults with any frequency.  The deaths are largely among those with limited life expectancy and have almost entirely substituted for flu deaths.  We cannot endure a continued upheaval of educational, social and economic life.  It is not good for our collective psyche to be subjected to round after round of terror and hysteria.  So brace up, and accept our inevitable fate of enduring periodic epidemics and be thankful that we do have the technical capability to fight CV-19 effectively, but also insist that the comprehensive welfare of the public as a whole be the polestar by which our fight must be guided.  No more lockdowns, no more school closings, no more mask mandates, no more of the futile, virtue-signaling measures which are not supported by data or any credible research.