Simply because a coronavirus test says that you don’t have the virus does not mean that you are not infected — or infectious.
You had any exposures that may put you at risk for coronavirus. A few days after you develop a terrible cough and feel somewhat short of breath and very exhausted. You take your temperature: 101 levels. A fever.
You suspect you may have COVID-19, the disease caused by the novel coronavirus. The days roll into one another, and your physician urges you to stay home unless your condition worsens. You are feeling pretty bad, however, and eventually, get an appointment.
They test you for flu by adhering a swab far up your nose, and you’re advised the test came back negative, you do not have flu. They tell you they’re saving the COVID-19 evaluations for people who are worse off than you are. You go home with a prescription for antibiotics, maybe because they do not know what else to do, and read about actors that are testing positive but do not seem so sick.
A few days later, nevertheless, with fevers, you return, and the physicians relent and examine you for SARS-CoV-2, the virus which causes COVID-19. They stick something up your nose into what feels like the bottom of your eyeball.
They inform you that the results will be offered in a few days and you go home and wait. Lastly, the results come back and you’re told you don’t have COVID-19. Now what?
This is a true patient’s story. In actuality, it’s lots of people’s story — at least a version of it. Round the planet, people with symptoms and signs of COVID-19 are analyzing negative and wondering exactly what it signifies. They aren’t showing up in the numbers, and they’re left in limbo about what to do next.
The issue may be with this test. Current coronavirus tests might have a particularly high rate of missing infections. The fantastic thing is that the tests seem to be very specific: If your test comes back positive, it’s nearly sure you have the illness.
The most common test to detect the coronavirus entails a procedure called a reverse transcription-polymerase chain reaction, or RT-PCR, a jumble of words that refers to a method capable of detecting virus particles which are generally present in respiratory secretions through the launch of an infection. From a technical perspective, under perfect conditions, these tests can detect tiny amounts of viral RNA.
In the actual world, however, the experience can be very different, and the virus could be missed. The top the Centers for Disease Control and Prevention will say is that in case you test negative, “you likely were not infected in the time that your specimen was collected.” The keyword there is “probably.”
False-negative evaluation results — evaluations that indicate you are not infected, as soon as you are — appear to be uncomfortably ordinary. More importantly, and disturbingly, I hear a rising amount of anecdotal stories from my fellow physicians of patients testing negative for coronavirus and then testing positive — or people that are almost certainly infected who are testing negative.
Unfortunately, we have very little public data on the false-negative speed for these tests in clinical practice. Research coming from China suggests that the false-negative rate possibly around 30%. A number of my colleagues, specialists in laboratory medicine, say concerns the false-negative speed in this country might be even higher.
There are various reasons a test could be negative under real-life problems. Perhaps the sampling is insufficient. That’s not a simple procedure to do or for patients to tolerate. Other potential causes of false negative results are associated with laboratory methods and the materials used in the evaluations.
So, where does this leave us? Despite more testing, we’re most likely to be underestimating the spread of this virus. For the time being, we should assume that anybody could be carrying the virus. If you have had probably exposures and symptoms signal COVID-19 disease, then you probably have it if your test is negative. We must all continue to practice the behaviors — strict hand washing, not touching the face, social distancing — that slow its own spread. And we need better information about the performance of the tests — including any new tests which are introduced — in the actual world.
Even as better evaluations emerge, we should always place the evaluation result in the context of the other information we have. It is a lesson that endures through medication: Look at the big picture, not just one bit of data. Triangulate on the fact, using all of the resources of information you have, no matter how great a single test. And do not be shy about questioning a decision that does not fully fit the facts.