Pre-Pandemic: Detection, Protection, Projection - A Pandemic Primer, Part 2

Back to the Future, Back and Forth: "If I knew then what I know now...should've, would've, could've...what were we/they thinking?!" If you haven't heard or said a version of one of these, I would be amazed. We all catch ourselves looking back, second guessing ourselves, more often others, and otherwise play 'Monday morning quarterback' ("I could have told them that wouldn't work...If they'd only listen to me..."). This is the second installment from the mini series I started just a few days ago, with some important acknowledgements in between. Okay, let's get down to basics...

False Positive, Negative - a One, Two Punch: When we set out on the mission of detection, it's of course useful to know what we are trying to detect, as well as the signs (i.e., symptoms) of the thing we are trying to detect, such as COVID-19, for example -- well, what did you expect, something out  of date, that we have already become highly aware of and protected (such as through vaccine programs, prophylactic measures, other forms of prevention)? As cases started getting diagnosed, we learned of the signs/symptoms you and/or others within six feet of you might be showing, manifesting. The signs and symptoms that would distinguish this virus from other conditions that might share the same symptoms, including other viruses. This, to minimize misdiagnosis and therefore either the wrong treatment or no treatment at all when it's called for, timely ( a recent radio commercial that aired around these parts emphasized "the only worst thing than finding out you have condition 'X' is finding out too late", after which the sponsors hoped you would run to your physician). We then started hearing about tests that were becoming available and the level of sensitivity of these tests. What they were tacitly referring to was tests that inherently had different levels of confidence intervals associated with them, in reducing both "False Positive" (Type I, over-diagnosis, indicating that you had CV-19 where you eventually find out you don't, aka errors of 'commission') as well as "False Negative" (Type II, under-diagnosis, missing CV-19 when in fact it's present in your system, perhaps not yet to a level the test at hand can detect, aka errors of 'omission'). It's not uncommon for both types of diagnostic errors to occur concurrently; that is, when diagnosing a condition when it's in fact not present, you might be missing another condition. Many times, this is a harmless, relatively benign situation, whereas in others it can lead to mistreatment, undertreatment, overtreatment, and even loss of life. OK, but at least there's only two types, sounds easy enough...

Time, Place, Person(s) - Supply, Demand, Serious to Silly:  It depends on the degree of potential harm, the severity of symptoms, and the sensitivity of tests, among other factors, in how one decides which type of diagnostic error you will tolerate more. Add to this the number of decisions one has to make, the window of opportunity, and the resources on hand to make such decisions, and you have a complex set of variables, dynamics with which to contend. Early in the pandemic, we heard advice on various news feeds: "...if you have a fever or a cough, just stay home and see...if it gets worse contact your physician..." And then we heard other advice as tests became available: "...testing for CV-19 has tremendous value in containing the spread...who should get a rapid test...rapid tests are considered most accurate in a patient with active symptoms...how people could still end up with CV despite a negative test...the variety of testing platforms for SARS-CoV-2 available can be rather confusing...". 

       This, followed by "...people getting medication X versus a placebo...if those getting medication X stay healthy with no side effects for _____ period of time...medication X has been temporarily taken off the market...medication X deemed safe and effective for people in _____ age group...". What we didn't overhear directly but learned later from those health care workers in ER's and other intensive care units, was the immense number of critical cases they were confronted with in a compressed period of time, with limited resources: "...we had to stretch our PPE's way beyond their intended life, not knowing how much safety this afforded ourselves and our patients...how to allocate the few ventilators we had and whether some patients could actually be made worse...having to literally make life/death decisions at a rate heretofore not experienced by even the most veteran...having to triage...not just straining our resources but our staff at a level we don't yet know the long term impact..." 

       More recently, while the arrival and gradual increase in PPE's, ventilators, and other life sustaining technology, and with the gradual decrease in CV-19 cases, along with the data accumulated throughout the past several months, have collectively given these health care workers a little more 'breathing room', it's still a highly intense process, this process of minimizing Type I/II diagnostic errors in order to decide whether to admit a patient at all, let alone where in the hospital and what level of care a patient will need in predicting even a short term outcome. And all this in the U.S., while in places like India "...a severe shortage of oxygen and other basic supplies has forced hospital workers...the ratio of health care workers to patients..." What we continue to hear and read (i.e., just the past few days: "...the CDC has now eased restrictions on mask wearing...CDC guidance prompts caution in some states whereas in others..." And, on the SILLY front, talking about shots, also from the past few days: "...the first bottles of 'Atomik', made from apples grown near the Chernobyl nuclear power plant are making their way to...we didn't detect any significant amount of radiation..."   

OK, enough of Type I/Type II for now, I think you have enough info. as a primer, at least I've had enough Typing myself, so time for a breather...perhaps a shot of Atomik to propel me into the next section...