Page 63 - JSOM Fall 2021

active-duty Soldiers. The purpose of this epidemiological sur- FIGURE 1 Symptom prevalence of sample (January 2020–
vey was to determine the prevalence of prior SARS-CoV-2 September 2020).
infection and symptoms of COVID-19 within a mechanized
infantry brigade.

Methods
Study Design and Setting
We conducted a retrospective, observational cohort surveil-
lance of a mechanized infantry brigade at Joint Base Lewis
McChord. Brigade medical personnel and preventive medicine
subject matter experts created a testing protocol and survey.
The institutional review board deemed the surveillance exempt
because of its nature as public health surveillance.

Sample Collection
From 30 June 2020 to 30 September 2020, battalion aid sta-
tions and the brigade clinic collected participant samples and
surveys. At battalion aid stations, medical personnel preregis- Outcome Measurements
tered participants for scheduled timeslots. Each participant was The primary outcome was the prevalence of SARS-CoV-2
preregistered with a tube label printed prior to their collection, anti body positivity in the convenience sample. The secondary
briefed by medical staff, and given the patient information sheet outcome measurement was the prevalence of participants ex-
and survey. Samples were transported in a cooler within an hour periencing symptoms of potential COVID-19 from January to
to the local medical treatment facility (MTF) for testing. September 2020.

At the brigade clinic, patients attending appointments with Data Analysis
unrelated, noninfectious complaints were offered participa- The surveillance team manually entered survey responses
tion at the end of their clinic visit. Brigade clinic lab staff col- into Excel version 16 (Microsoft, https://www.microsoft.com
lected and transported samples. Unit medical providers called /en-us/microsoft-365/excel) and then destroyed the paper
all participants to inform them of their lab results. copies. The primary investigator reviewed all surveys to en-
sure accuracy of data entry. Participant military occupa-
Selection of Participants tional specialty (MOS) was defined, in accordance with FM
10
We enrolled a convenience sample of Soldiers who underwent 3-90 Appendix A (Army Branches and Tactical Echelons).
SARS-CoV-2 antibody testing in a mechanized infantry bri- The “medical” occupation was categorized separately by the
gade. Inclusion criteria required participants were ≥ 18 years primary investigator as a MOS that directly renders patient
and assigned to the brigade. Participants were excluded if they care. Examples would be 68W (combat medic specialist), 62B
had contraindications to venipuncture such as fear of needles (field surgeon), or 65D (physician assistant). Analysis was per-
or if they had screened positive for symptoms of COVID-19, formed with Excel Analysis ToolPak.
as defined by the Centers for Disease Control and Prevention
(CDC), in the previous 14 days from collection date (Figure 1, The “respiratory quarters” was a specific quarantine pro-
Table 1). The decision to exclude participants with symptoms cedure implemented by this brigade for Soldiers exhibiting
of COVID-19 in the last 14 days was to protect other partic- symptoms of potential COVID-19 who had no confirmatory
ipants and medical staff from potential COVID-19 exposure. laboratory testing. Prior to and in the early surveillance period,
participants could not receive lab confirmation of COVID-19
Methods of Measurement for their symptoms as they did not meet criteria for testing.
The lab tested serum samples with the Elecsys Anti-SARS- Rationing of NAAT SARS-CoV-2 testing was reserved for hos-
CoV-2 (Roche, https://diagnostics.roche.com/us/en/products/ pitalized MTF patients, elderly, and those with comorbidities.
params/elecsys-anti-sars-cov-2.html). qualitative antibody test, Thus, if displaying symptoms of COVID-19, Soldiers were
which was the most compatible test with the MTF chemistry placed on respiratory quarters for at least 10 days with im-
analyzers (Figure 2). Elecsys Anti-SARS-CoV-2 is a CLIA for proving symptoms and either 72 or 24 hours if afebrile.
the in vitro qualitative detection of antibodies (including im-
munoglublin G) to SARS-CoV-2 in human serum and plasma
(Figure 3). The assay uses a recombinant protein representing Results
the nucleocapsid (N) antigen to identify antibodies against All of the returned surveys had a 100% question completion
SARS-CoV-2. Results are reported as “positive” or “nega- rate for 264 respondents (Table 1). Among respondents, the
tive.” The FDA approved emergency use authorization of the median age was 26 and 164 (55%) were male. A total of 51
assay. The assay results take 18 minutes. 9 (19%) lived in barracks, and the median body mass index
(BMI) was 27. Only one (0.4%) participant had diabetes, two
A paper-and-pencil survey questionnaire incorporated par- (0.8%) had asthma, and 13 (5%) had hypertension. A total of
ticipant demographics, symptoms of COVID-19 since Jan- 146 (55%) participants were in “combat arms” occupations,
uary 2020, and history of quarantine as a trace contact and 34 (13%) were in “medical” occupations.
(Figure 4, Table 2). Participants self-reported for symptoms
of COVID-19 on the survey. The survey was a combination of The sample demographics were compared to the brigade de-
short answer, multiple-choice, and yes/no questions. mographics of ~ 4,800 Soldiers using two-sample, two-tailed

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