There Won't Be Enough COVID-19 Tests,
So Use Clinical Symptoms as a Guide
BY MARK MOSLEY, MD, MPHThe
availability of COVID-19 testing is held as the linchpin for many of us waiting
to know how to best protect our community, but we must be careful about
thinking of COVID-19 testing as our only good option.
What do we do before testing becomes widely
available in our communities? What if you practice in a remote or rural area
where COVID-19 tests may not be readily available? What if multiple companies
produce COVID-19 tests to meet demand, but they haven’t been sufficiently
vetted or they simply have different testing characteristics that make them
highly variable from each other and end up being confusing rather than
The validity of the test will depend on the
clinical pretest probability. What if we fail to make the distinction between
screening asymptomatic people and using that as a piece of the picture for patients
who are clearly sick?
What happens if we are
testing, but some link in the chain breaks? We could run out of reagent,
transportation lines could be disrupted, reporting could become significantly
delayed, HIPAA violations could prevent sending results by phone, and the
economic crisis could prevent having a phone or paying for a cellular plan.
What happens if those
in drive-by testing spots are not trained well or not able to obtain a proper
nasal specimen? Do we allow people to self-swab? Can the test be operator-dependent?
reinfection? Will the test lose some of its testing characteristics if the
viral load is less? How many of the “positive” COVID-19 tests are asymptomatic
carriers? What about false-positives? Eighteen percent of COVID-19-positive
patients on the cruise ships were asymptomatic. Did they actually have the
virus? Can a single “negative” test be trusted in a sick
patient? The PCR measures viral genomic material, but doesn’t necessarily indicate
The CDC said a patient who
has tested positive must have two consecutive negative COVID-19 tests to be considered
negative because negative RT-PCR does not exclude COVID-19, especially early in
the course. (Read a brilliant review of the statistics, including false-negatives,
by Andy Chen in Towards Data Science. Feb. 15, 2020; https://bit.ly/2QDrH2E.)
The amount of resources eaten
up to retest results we don’t believe will be untenable. The increased testing,
especially if we screen asymptomatic people driving through testing sites, may
actually increase confusion. Some are calling for testing only hospitalized
patients, select frontline staff, and certain households and institutions with
very high-risk residents. (Figuring out this last one out will be difficult.)
We should be recommending less COVID-19 testing instead of more, or at
least targeted testing instead of mass screening.
Some of these
questions and many others are critical to consider. What should we be doing in
the ED if COVID-19 testing becomes less helpful than we are hoping? What should
we do then? We should do what we have always done best: Use our bedside
clinical acumen to know who to test and how to use the test.
Now, more than ever in our entire careers, we
must not get swept up in blindly following someone’s protocol and turning off
our brains in the process, especially when the “protocols” are changing every
day. They are also not consistent from hospital to hospital or from clinics to minor
emergency clinics. The protocols are not even consistent from the CDC to state health
departments to local health agencies to the corporate rollouts that own the
Everything, at least
in the ED, begins with a triage decision based on the likelihood of disease, and
that is not an automatic one-way door. It is like peeling an onion. The ED health
professional back in the room is another layer that does triage (or sorting),
again by using a detailed history and physical to make a differential diagnosis
with high and low probability. We use clinical decision-making that may or may
not require testing. We are the best prepared in this crisis to know how to
drive in this lane.
I am not a virologist,
an infectious disease specialist, or a pulmonologist; I am an average EP in
Kansas. I am not offering a scholarly contribution as much as I am offering an
emergency toolkit to break out in emergencies. A few clinical things that we and
our patients should know mostly come from a single study (New Engl J Med. 2020
Feb 28.; https://bit.ly/2QGOnPH):
Many of the symptoms attributed to COVID-19 are rare:
- Conjunctival involvement: <1%
- Rash: <1%
- Cervical lymphadenopathy: <1%
- Diarrhea: <4%
- Nasal congestion and runny nose: <5%
- Nausea and vomiting: 5%
should be mentioned that the American College of Gastroenterology just reported
a small study from China in which diarrhea was present in 29 percent of 204
patients. (Am J Gastroenterol. 20 March 2020; https://bit.ly/3bd3Grg.) (Someone smarter
than me will have to tell us how to compare 29 percent of 204 compared with
four percent of 1099.)
was initially present in less than half of patients (44%), so its use as a
dichotomous screening tool will fail. A total of 89 percent did end up having a fever
at some time during their hospitalization, but the fever, contrary to hearsay,
was not necessarily high—the median axillary temperature was 37.3°C.
symptoms must be clearly defined to include cough and difficulty breathing as
well as sore throat.
This is important because not everyone had cough (68% did).
shouldn’t be doing a strep test on everyone. Only 15 percent presented with a sore
in most patients should still look like the flu. Severe malaise was
present in 38 percent of patients. Myalgias were seen in 15 percent,
particularly in the legs in children and in the back in adults, and were seen
in extraocular muscles, which may present with pain behind the eyes or
photophobia and headache (14%). (Iran J Med Sci. 2017;42:2; https://bit.ly/3dpMwZq.)
doxycycline, not azithromycin, if a patient has COPD or smoker’s bronchitis and
a change in sputum production (34% with COVID-19). Secondary bacterial
pneumonia in the 1957-1958 U.S. influenza epidemic was two to 18 percent. Staphylococcus aureus was a primary pathogen in the
1968-1969 influenza epidemic. Doxycycline will
treat strep and staph, including MRSA; azithromycin won’t.
use steroids if you can avoid it. During the 2009 influenza pandemic, 35-55
percent of patients admitted to the ICU in Europe had been placed on steroids,
and that may have been related to increased mortality; it was a retrospective
study, which may suffer from acuity bias. (J Infect Dis. 2015;212:183;
this critical time not just to mention but actually teach smoking cessation and
about secondhand smoke exposure. If ever there was a time, it is now. It may
have played a major factor in morbidity and mortality throughout the world. If
you don’t know how to teach smoking cessation, you can learn it or hand out
resources that can do it for you.
define high risk and low risk, and make a distinction between infection and
elderly are not at high risk for infection, but are at high risk for death if
exposed. Young children are at high risk for infection but very low risk of
death (0 in the 0-14 age category in the China study). Health care workers are
also at high risk for infection but very low risk for death (0.3%) Pregnant
women are apparently at very low risk of death. (This differs from some of our
x-rays are not diagnostic. Eighteen percent of hospitalized COVID-19 patients had no radiographic
abnormalities, but 95 percent of critically ill patients did. You are probably going
to get a chest x-ray on them anyway.
of this information comes from one study in China of 1099 hospitalized COVID-19
patients, a select cohort from 7736 patients. Some of these percentages will
likely change. Don’t sue me; we all know this is a moving target, and some of
this will need to be tweaked even minutes after it is published!
use the scientific data we have. Let’s use the clinical expertise we have
acquired throughout our professional training. Let’s not allow some uncertainty
to lead to irrational “protocols” on a kneejerk-triaged patient. But there are
some recommendations we cannot do enough: Wash your hands, and make those 20
Mosley is an emergency
physician in Wichita, KS.
Read all of EMN’s breaking COVID-19 coverage at http://bit.ly/COVID-19-EMN.
updated on our new COVID-19 articles by following us on Twitter @EMNews.