This is the continuation of a series of journal entries depicting what it’s like to be a part of the COVID pandemic from the medicine resident perspective.
Sunday, March 29th
Although I’m a resident and I’m able to access my own medical chart through the electronic medical record, I’m not allowed, per hospital policy. I’m relegated to waiting for my results once “released” to me. While waiting for results in self-isolation, at a certain point you don’t really care whether it’s positive or negative, you just want to know something. Unfortunately, we still don’t know if being coronavirus positive prevents you from getting infected again so I’m not at the point where I would prefer to be positive just to get it over with.
Finally, five days after having the back of my throat swabbed I get an email saying my results are back: SARS CoV-2—undetected. Whew, negative. I was able to isolate for 5 days while my wife worked and took care of our baby simultaneously. Many other households aren’t that fortunate and either the other parent would have to take unpaid time off from their job (if they are able) or the person in quarantine would have to watch the kids and therefore expose the entire family to coronavirus. This is problematic for many obvious reasons.
The responsiveness from the government to obtaining and manufacturing tests was bungled from the very beginning. Quick turnaround time for testing is beneficial for giving patients a diagnosis promptly and is beneficial for epidemiologic prediction models that guide how much a region will be impacted and which locations that will be hit hardest next.
There are two main testing locations. In-patient testing for those that are hospitalized, where the test is performed in the hospital’s own microbiology labs (“in-house”) which have continuously improving turnaround times. Once the tests became available to hospital labs across the country, waiting times went from 48 hours down to about 4 or 5 hours (and in some hospitals turnaround is under an hour). The other main testing sites are commercial labs (LabCorp, Quest Diagnostic, etc.), where your test would be performed if your outpatient doc sent in a referral or if you went to a screening center. Unfortunately wait times are getting much longer as the public demand goes up for testing, and along with it, any part of the supply chain that is lacking—from swabs to reagents to protective gear for the providers—will back up everything.
The answer to better prediction models and better care isn’t just faster turnaround time for tests. The media has really honed in on getting quick results as a major issue in the epidemic because the news can show a long queue waiting to be swabbed or interview people frustrated by the lack of knowing their status. Arguably just as important is the accuracy of these tests. Swabs of the nose and throat are analyzed by something called polymerase chain reaction (PCR), which is designed to multiply the virus genetic material—RNA in the case of coronavirus—and detect the presence of the virus itself. A couple of problems arise from PCR as there have been reports of high rates of false negatives—meaning getting an inaccurate “undetected” reading when in fact, one is coronavirus positive. This is called low sensitivity in a test.
Because PCR looks for the virus itself from the swab, there have been studies in which essentially, if you go lower down the trachea (“wind pipe”) and obtain a sample closer to the lungs there are higher concentrations of virus located there so you will get a better sample and potentially provide more RNA material to amplify and detect with PCR. The issue with going down the trachea, in addition to being very unpleasant, can cause more of the virus to be coughed up during the procedure potentially infecting more people. So it seems not only possible, but likely that the swab going to the back of the throat either by way of mouth or nose just doesn’t pick up enough virus to be amenable to detection in many instances.
A blood test was recently approved by the FDA under Emergency Use Authorization which will test for antibodies (our own immune system response to the virus). These tests are already in use in China and other countries and can return results in under an hour. The benefit is that these tests aren’t dependent on obtaining an adequate swab and they could potentially tell us if someone’s been exposed in the past. It will also lead to more data regarding immunity to future infections with SARS CoV-2. The downside is that the test may not be accurate either and potentially detect non-COVID-causing coronavirus like CoV-1. There also arises questions like: is it better to know with 80% accuracy with one method vs 70% accuracy with another but it takes half the time to get the results back? There are no clear-cut answers because there are pros and cons to both.
The good news amongst all of this is that there is high “specificity” with these tests, meaning that if you get a positive result then you almost certainly have COVID, however comforting that may be. Keep in mind, for the time being these only apply to people that are having symptoms. I haven’t even touched upon the messed up screening guidelines and how they’ve morphed over the past few weeks. All of this is really to say we don’t know how many people are SARS CoV-2 positive currently for lots of reasons, and looking at the current positive cases on the news only tells part of the story.
At our institution there have been patients that we’ve been so sure are COVID positive that we’ve performed multiple PCR tests yet have all returned negative. Unfortunately, the answer to those that are so sure they are positive with coronavirus but have received negative testing is to assume the test is wrong. Given the rapidity with which this is all developing there just isn’t enough data regarding how accurate these tests are and how they should be employed.
I finally received a call from occupational health telling me the test results and to go back to work. Typically I’d be starting on outpatient weeks at this time, meaning I would be seeing patients in the office and go to morning and afternoon conferences with other residents. The pandemic has disfigured outpatient life for a resident, so now I start with telemedicine appointments and we’re given strict instructions to stay away from the hospital until it is our turn again—I’ll gladly oblige.