The virus bullets that you don’t hear

I often live in denial as much as anybody. When I see an ant crawl across my tablet screen, I crush it and say, “Huh! I don’t like that.” But then I have to kick myself into gear to admit that it is time to go searching for more ants. A lot of people in low COVID-19-count communities and their states’ governors have been living in similar denial. If I don’t go looking for ants, then there are no more ants!

After two months of Federal government inaction and two more months of often-ineffective local lockdowns, there five important numbers regarding the novel coronavirus that we still do not know. And we do not know them largely because we have failed to expand coronavirus testing beyond the already sick and the knowingly exposed.

The asymptomatic carriers of this virus are, to use an old war saying, the bullets that you do not hear. And yet, these are the people who will continue to spread the virus for many months to come into workplaces, nursing homes, churches and other places where people congregate.

Bring on the auditors

Let me suggest that every county health department needs to engage a local CPA firm to help them devise a statistical sampling strategy for their communities. Licensed auditors go into companies every day to find flaky account balances and inaccurate inventory levels, not by counting everything, but rather by using basic statistics.

When you have a limited amount of resources, whether auditor hours or coronavirus tests, it is quite easy to calculate how far you can stretch them as still have a good chance of finding that “unheard bullet” before it hits someone. The number of samples you need to take to get usable data is likely smaller than you might think.

Recall this old parlor game. You have a group of, say, 25 people at a party and you instruct your guests to go around telling each other the day of the year on which they were born. What are the odds that two people in attendance will find their “birthday doppelganger”? There are 366 different days in the year on which to be born. How likely would two of these people share the same birthday? It turns out that, with just 25 guests, the odds of this happening are over 50%.

County health staff should be randomly hitting workplaces, bus stations, and other places people gather to offer a small number of free virus tests. And not primarily to save that random person found (although that is a good side effect), but rather to get a statistical profile of where potential “hot spots” are. In this game of “Where’s Waldo,” the odds are actually pretty good that, even in low-case-count areas, you will find a “Waldo” with a limited number of samples. And that result will tell you where you need to do more testing. And if you don’t get a “hit,” that is important information as well. You gain a lot more confidence about the safety of that tested space, as opposed to assuming that “there are no ants here.” At least as of today,

What we still do not know

1. The number of asymptomatic “Typhoid Marys” that are out among us. It is perhaps a good sign that, where confirmed  COVID-19 cases have been very concentrated, a majority of carriers show few, or even no, symptoms (in this sample, between 50 and 75% of infected soldiers were asymptomatic). The bigger the number here, the smaller is the actual fatality rate of this virus. But these carriers do infect others, so we need to find out who they are. The more random sampling we do, the better this estimate becomes.

2. The true R-naught (R0). R-naught is the measure of how many additional people the average virus carrier infects. When this number gets above 1, then you will get the exponential growth in transmission that we have been seeing. But as just noted, the more people that we detect early with the virus, the more that R-naught appears to decline, which is a good thing. Isolation and social distancing can also drive this number down below 1, so these countermeasures are critical. Again, we need more random sampling to get a better handle on the “true” R-naught.

3. The true case fatality rate (CFR). Nationally, this number has been running over 5% as a percent of confirmed cases, a horrific number. But (is this good news?) if we are only detecting half of the cases, then the CFR drops in half as well. I wrote about “the missing coronavirus tests” over two weeks ago. We either have an incredibly lethal virus here or we are still very ineffective at detecting cases. Take your pick. And it could be both.

4. The number of people who are carrying effective antibodies. Antibody tests to verify the “cured” survivors are only just coming out in any quantity. However, their accuracy seems to still be questionable, and whether having coronavirus antibodies makes you immune from further infection is still not known. Random antibody tests in large numbers of people would tell us a lot about how many people have actually been infected, and perhaps how many people “could go about their daily business” at lower risks of infection while the rest of us hunker down.

5. The number of smoldering “hot spots” currently undetected. Rural state governors, especially, have seemingly been in denial about the extent to which workplaces, correctional facilities and elder-care centers have already been hit, even as large outbreaks appear “as if out of nowhere.” Random testing of all of these places would have given some measure of warning, but this is still not being done in many places.

Unfortunately, we really do know where the future “hot spots” are. Prisons, meatpacking plants, nursing homes, as well as the families of those brave/desperate/no-choice front-line workers, likely already have many more infections among them than we know about today. It just takes some proactive sampling, foresight, and testing money spent by state officials, which have all been sorely lacking.

2 thoughts on “The virus bullets that you don’t hear

  1. Lisa

    Unfortunately, the foresight should have happened long ago, after successive polio outbreaks in the mid-20th century. Or more recently, the HIV pandemic? No, wait, maybe the original SARS outbreak? H1N1 flu pandemic? Ebola? Zika anyone? I view this as much a failure of our (underfunded) education system, the popularity of fundamentalism that transfers personal responsibility to a higher being (“God’s plan”), except when humans behave badly of course (“God’s punishment”), religious explanations for natural phenomena creeping into secular textbooks and lesson plans, inept “leadership” among elected federal officials and political appointees, past and present, and a failure of the federal government to anticipate, plan, fund scientific research, stockpile, address potential supply chain issues, and budget for crises like the COVID-19 pandemic.

    Most states have balanced budget provisions, so absent an injection of federal funds (vs. a disinfectant), those budgets will need to be cut fairly dramatically. Some cuts are easy now, for example Medicaid payouts are lower because elective surgery has been curtailed, and people have been afraid to got to their doctor or clinic out of fear of contracting COVID-19. However, as state restrictions are lifted (and COVID-19 infections presumably go up), reimbursement requests will increase, but sales tax receipts will likely stay below baseline.

    Regarding the diagnostic and serologic tests themselves, it doesn’t help when high-profile academic institutions like Stanford release studies with serious sampling and methodological issues. Special interests latch onto those studies to make a point and use the media to amplify their positions, but the fact that the research was flawed and the authors doubled down vs. following sound scientific research practices, is conveniently omitted. https://www.mercurynews.com/2020/04/20/feud-over-stanford-coronavirus-study-the-authors-owe-us-all-an-apology/

    Reply
  2. Pingback: The ethical theory of “Sucks to be you!” – When God Plays Dice

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.