Since mid-March, there has been much focus on the immediate future and “the curve.”  Whether the curve has been flattened or not, we are reopening the economy and that has sent a signal that normality is returning. However, what will likely happen in the next month or two is woefully inadequate information for planning. For the immediate future, the only thing that will change is people’s behavior. The coronavirus may wane with the change of seasons, but that is unknown. Behavior and seasonality are the two main variables that control our future.

Before January 1, or thereabouts, there was 100 percent susceptibility to this new virus in the United States. In other words, we can assume that it had not come to the country previously, and no one had contracted the virus. Therefore, no one had gained immunity. Many of the models that scientists use to predict the infection case rate, or the mortality rate, are based upon numbers of susceptible, exposed, infected, and recovered cases. As more and more people are infected and recover (or die), the portion of the population which is susceptible decreases.   

The number of reported cases in Bexar County appears relatively low in relation to the population, but there is a considerable undercount. We now clearly know that there are many asymptomatic cases, which helps explain the rapid spread of this virus. Estimates of the proportion of positive cases that are asymptomatic range from one-fourth to more than 90 percent. Witness recent studies in prisons and jails, including Bexar County

But does the reported case count constitute all our symptomatic cases? Not nearly. Early on, people with symptoms were denied the test as there were few test kits, and the tests were saved for hospital patients. (The editor of this publication has attested to this.) We must also consider that all virus tests produce some false-negative results, and that there are those who have mild symptoms and never attempt a test but in fact have the virus.  

Recent work with serotyping antibody tests is telling us that the true number of cases is maybe 50 or even 100 times higher than the reported counts. If we use the 100 factor, we have had over 200,000 cases in Bexar County. By that estimate, there remain 1.8 million susceptible people in Bexar County.

What will happen to all those susceptible people? They will contract coronavirus, recover, and gain immunity; or perhaps die – or they will stay out of harm’s way until a vaccine can be developed. So why not allow the virus to run its course? There are many reasons. If you think there’s economic chaos now, imagine our hospitals overflowing with people about to die. Think businesses closing because no one is well enough to open them. Think of entire families becoming sick, or even entire families dying. All of this is happening around the world on a much smaller scale in areas where exposure control was exercised late, and the virus gained a large foothold.

We dodged a bullet. However, we are about to run a new experiment. Models, even the Trump administration models, predict far more fury in the months to come than we have seen.

The only variable that might mitigate this is seasonality, a wildcard. Almost all cold and flu-like viruses seemingly disappear in warmer weather. The four human coronaviruses that cause colds wane in summer. We don’t know if coronavirus will do the same, but if it does, that would reduce its transmissibility and give a much-needed break. Of course, if we have no vaccine in the fall, the pandemic will be expected to accelerate with fall weather. 

Eventually we will have a vaccine. A vaccine is not necessarily a panacea. We know the flu vaccine is usually around 50 percent effective and also reduces symptoms in those who get the flu even after taking the vaccine. But the development of a vaccine within one year is a long shot and several billion copies of an approved vaccine will not suddenly appear.  

So-called herd immunity will increase, which means that, as you go about your daily business, your odds of bumping into an immune person increase, and your odds of bumping into a susceptible person decrease. But we need the number of susceptibles to fall far below 50 percent. That means a lot more cases and mortality. Allow too many people to mingle at once, and therefore, cause too many people to become sick, and hospitals will become overwhelmed. This is what constitutes a second wave. These were seen repeatedly in the 1918 flu epidemic.    

Since far more people survive coronavirus than die from it, it is especially important to look carefully at those who are at most risk of suffering fatal effects of the virus. We start with the elderly. If you are retired and on a fixed income, it is best if you do not interact with anyone, including relatives outside of your household. If you are obese, have diabetes, if you have had a stroke or heart attack or high blood pressure, or if you have lung disease, then you should not risk exposure.  

Do not go ahead and be exposed just because the economy starts to open. Nothing has changed about the virus because the economy has partially opened. The risk to you is as great today as it was last month, and as you interact with more people, the risk increases considerably. 

Some of the attempts to model the spread of this virus are based upon some concept of how people socially interact. That is difficult to predict, but the bottom line is that the fewer people you encounter, the lower your risk of contracting the virus. Therefore, social distancing is key.  

And that brings us to other prerequisites for reopening, like testing. We must test anyone who is even slightly expected of having the virus because of contacts, and negatives should be tested twice, preferably with a different test, to reduce false negatives. Tests for medical personnel and first responders (including necessary retail personnel) should be copious. In addition, we need a reliable serological or antibody test to determine who is immune. These tests will allow us to estimate the true number of past cases. This will make modeling and planning vastly better. If serological treatment (transfusions of antibody laden plasma) proves effective, we need to identify these people through antibody testing. 

Think of each person who becomes infected as a pinball. Who will he bump into next? If we increase testing to identify more cases earlier, then we can remove not only the pinballs, but anyone else that the pinball contacted. These principles are hallmarks of outbreak control. Anyone who is sick must have the option to isolate in a safe place to spare loved ones, co-workers, etc. from exposure. Isolation should not have a bad connotation. It must be an easy option to exercise.

I said earlier that the main way to decrease the susceptible pool of people is to allow them to get infected and recover. Then why all these controls? Other than saving the hospital system from complete chaos, there is the need to reduce the susceptibles in a controlled manner. It is a balance between the risk of coronavirus effects and the risks associated with diminished economic activities. Both have consequences, but if we can keep those who are at greatest risk out of harm’s way while opening more businesses and social activities, then we can have a maximal effect on keeping mortality low. We do that through testing, tracing, tracking, and isolation.

There is not a lot of joyous information here. The point is to realign expectations, as many folks seem to think that normality soon will return. It will not. Use this information and plan accordingly. Ask questions of professionals, your elected officials, city workers, health personnel. On the bright side, in 1918, there was no flu vaccine. Medicine was a shadow of its current self. There was tremendous loss of life around the world; perhaps 50 million deaths compared to 340,000 estimated as of mid-May for COVID-19. And yet preliminary estimates are that coronavirus is as communicable and deadly. Why the difference? Because we have instituted exposure controls that are working. We need to continue and not let our guard down as we reopen the economy.

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Jimmy Perkins

Jimmy Perkins, Ph.D. is a retired professor of environmental health sciences and former Dean of the San Antonio Regional Campus of the University of Texas School of Public Health. He spent 35 years teaching,...