The Christian Chiropractor Commentary

The Never Ending Pandemic? A Tutorial in Arm Chair Epidemiology

              It is my goal in the next couple pages to turn you into an amateur epidemiologist, someone who studies and understands how diseases spread.  In the end I want to use our discussion to come to some conclusions about our current situation with this pandemic.  We have real reason to be both fearful and hopeful.  In order for me to effectively turn you into an epidemiologist I am going to need you to you give me one thing and for you to do one thing.  First, I need you to give me the same trust you do as my patient, trust that what I’m going to explain is good science, obtained from very credible scientific sources, and completely trusted by me.  If you trust me as a doctor you can trust me as a writer, but still differ from me on my conclusions.  Second, I need for you to set aside any non-scientific theories, beliefs, hunches, and feelings you may possess regarding the subject of disease and disease transmission.  In other words, I need for you to be a scientist along with me for a few minutes, look at the data, and decide what that data really means, as opposed to what we might like it to mean.  Ready?  Here we go. 

              First, we need to understand that not all corona viruses are the same, called variants.  We are going to use the name of the disease, COVID19, as the name of the virus that causes the disease, because typing SARS-Cov2 is laborious.  When COVID19 first hit we were able to figure out that when each person got infected, whether or not he was symptomatic, he would spread the virus to 2-3 other people before recovery.  Most of this spreading happens in the first few days during which we “shed” viruses prior to having any symptoms, that is if we have symptoms.  This number, 2-3, is called the base reproductive rate or R₀ (R-naught).  Therefore, in the absence of preventative measures such as vaccines, masks, and social distancing, the base R₀ of the native or non-variant COVID19 is 2-3. 

              But, as you know, we are no longer dealing with the native COVID19, with more than 90% of all infections in the U.S. being caused what is called the Delta variant, or what I’ll simply call the Delta.  The R₀ for Delta has been calculated to be somewhere between 6 and 9, a lot higher than the native virus.  With this information I’m going to perform some simple math to demonstrate the difference between the native and Delta variants.  You may have had native COVID19.  If you did, according to the data, on average you passed on the virus to 2-3 people.  We’ll use 3 for this demonstration.  Those 3 people then gave it to 3 more people and so on and so on.  If we carry out this exercise 10 times (or 10 infection cycles), in the absence of preventative measures, we end up with 177,000 infected people that can be contact traced back to you.  Now consider that COVID19 has been shown to be 2% fatal and do that math.  2% is a relatively small mortality rate as infectious diseases go, yet out of those 177,000 as many as 3,540 died.  Obviously these numbers are inexact approximations and don’t take into consideration the dampening effect of intervention efforts such as contact tracing, isolation, quarantine, masks, and social distancing.  Even if the numbers are smaller, the point is still that these are serious numbers that deserve serious consideration. 

              Now let’s go through the same exercise with the Delta, using 8 as the R₀.  The results are shocking and almost unbelievable, but explain just why Delta is such a concern to you and I as amateur epidemiologists.  After the same 10 infection cycles, without interventions, we now have the entire population of the planet infected, over 8 billion people.  Since we don’t really know the precise mortality rate of Delta, we’ll use the same 2% which is a reasonable assumption, and end up with 160 million dead across the planet.  Rest assured we are not going to end up with 160 million dead bodies at the end of Delta because we do have interventions, masks, social distancing, contact tracing, isolation, quarantine, treatments, and since the beginning of the year, vaccines. 

              Looking specifically at preventative interventions, if you isolate a single sick individual, it prevents him from infecting others.  If you isolate a sick community, it prevents it from infecting the neighboring communities.  Isolation works very well, but is unpopular and we are tired of it.  Masks are another preventative tool, certainly less effective than isolation, but easier to tolerate.  However, masks have become political rallying points.  Therefore, although we will need to continue to use these tools, to count on isolation and/or masks to end the pandemic is folly.  Therefore, there are only two other options; let all the people on earth get sick until some sort of herd immunity prevails; vaccines.  I would argue that both will be needed to get us to the end-game, which can be defined as that moment when the effective R₀ value, called the R_e, is reduced to less than 1.  The R_e is essentially the R₀ value while taking into consideration preventative interventions, in this case vaccines.  The idea is that once each person spreads the disease to fewer than 1 other person, the virus has nowhere to go, and the pandemic ends.  I’m now going to explain why this could have happened with the native virus, but will be much harder with Delta, at least with the tools (vaccines) we have right now.  Back to math.

              The formula goes like this, R_e=R₀ * (1-X*V_e).  To calculate the effective reproductive rate of a virus you need to know it’s base reproductive rate (R₀), the proportion of the population vaccinated (X), and the efficacy of the vaccine (V_e).  Knowing that we need the R_e to be 1 or less in order to squash the pandemic, and we know the R₀ of the native variant is 3, and that the vaccine efficacy against the native variant is 95%, how much of the population did (notice I said did) we need to have been vaccinated in order to have stopped the pandemic prior to Delta.  If you do the above equation and solve for X you find we would have needed 70% of the entire population, including children, to have been vaccinated to have reduced the R_e to 1 and have stopped the pandemic.  But in slipped Delta.  Plus, in stormed vaccine hesitancy.  Spice this up with the fact that we still cannot vaccinate children under 12, and you have a completely new ball game.  The numbers we just solved for no longer matter.  Here’s our new situation.

We’ll use 8 as the R₀ for Delta and we still want an R_e of 1.  We don’t really know the efficacy of the current vaccines to Delta, but numbers I see vary from 67% to 88%, so we’ll choose 70% for the sake of our discussion.  If we solve for X we find that under the above circumstances we need 125% of the population to be vaccinated to stop the pandemic.  Uh oh. 

              Of course, those numbers are approximations, not real life, but they clearly demonstrate that despite how fast the vaccines were deployed, they were not quick enough for the fast mutating virus to develop its own work-around.  So now what do we do?  Well, they are already testing a new formula for the vaccine specifically against Delta, as well as a cocktail of mRNA strands for multiple variants of concern.  Both companies say they can roll out a new formula in 100 days.  Until that time we will start getting boosters of the original vaccine to up our odds as well as to continue to try to get more shots in more arms.  We will wear masks and argue about wearing masks.  We will see the surges come and go, wax and wane.  We will cross our fingers as kids get back together in school.  We’ll pray no worse variants emerge. 

              Now let us leave the world of the known and enter the world of the unknown, looking into the 4^th quarter, the likely time-frame when the new Delta-specific mRNA vaccines will be available and assuming we don’t get any new variants that defy the vaccines.  Let’s assume that the coming Delta vaccine will have a 95% efficacy against Delta like the original vaccine had for the original native virus.  In this hopeful yet realistic scenario, how much of the populace now needs to be vaccinated to get an R_e of 1?  Short answer: 92%.  Short summary, not going to happen. 

              So what do we do now?  Simply, we keep on truckin’.  We mitigate.  We vaccinate.  We argue about vaccination.  We mask up.  We argue about masks.  We treat the sick.  We develop new therapeutics.  We pray for the safety of our kids and grandkids.  We say goodbye to more friends and loved ones.  We suffer long-COVID.  There’s an awful lot of really awful long-COVID.  Eventually, maybe next year sometime, when enough people have enough antibodies to enough variants then COVID19 will work into the background.  We’ll slowly begin to take off our masks layer by layer, community by community, country by country.  We’ll return to a new normal.  As good as we did in 2020 we missed our one chance to stop the pandemic cold in early 2021 while COVID19 was relatively less contagious.  We moved so fast but a bit too slow for a faster-moving virus.  Now we have to learn to live with it, hope for no worse variants, sit back and wait.  We don’t know what that day will look or when it will be, but I think we’ll know it when we see it. 

In the meantime, remember what I’ve written before.  To my way of thinking it’s never been about me.  This entire pandemic has always been about the most at-risk, the most fearful, the most innocent, and everyone else in my life I care about, including you.  This is why I got vaccinated in January.  Regardless of personal motivations, the best thing you can do to protect yourself from COVID19, severe disease, hospitalization, ICU, intubation, and long COVID is the same thing, get vaccinated.