Page 72 - JSOM Summer 2023

Stability of SARS-CoV-2 on the
Army Combat Uniform and Recommendations for Cleaning

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Charmaine Ibarra, MS *; Lyteasha Bass, MS ; Eldad Saler ;
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Renae Daniels, MPH ; Norman Davis ; Michael A. Washington, PhD 6
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ABSTRACT
SARS-CoV-2 is the virus responsible for the disease that is remove coronaviruses from textiles. Most viral stability stud-
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known as COVID-19. While there have been numerous studies ies have been performed on standard clothing materials and
detailing the survival rates of SARS-CoV-2 on various materi- hospital- issue personnel protective equipment. 9–11 In the de-
als, there are currently no published data regarding whether ployed environment, U.S. military personnel are most likely to
this virus is stable on standard military uniforms. Conse- wear some version of the U.S. Army Combat Uniform (ACU).
quently, there are no standard operating procedures for wash- The current version of this uniform has been designed with the
ing uniforms once exposed to the virus. This study aimed to operational camouflage pattern (OCP). This uniform comprises
determine whether SARS-CoV-2 could be removed from Army 50% nylon and 50% cotton material. Permethrin is added to
combat uniform material by washing with a commercially these materials at 0.52% weight per weight to repel insect vec-
available detergent and tap water. Washing the fabric with de- tors. No published studies are addressing how to best remove
tergent followed by a rinse step with tap water effectively re- SARS-CoV-2 from ACUs. This is problematic given that ACUs
moves detectable viral particles. Importantly, it was found that are worn by physicians, military medics, physician assistants,
washing with hot water alone was not effective. Therefore, it and nurses while treating patients in the field. This study aimed
is recommended that military personnel wash their uniforms to provide baseline data for recommendations on uniform wash
with detergent and water as soon as possible after exposure to procedures following exposure to COVID-19-positive patients
SARS-CoV-2; hot water should not be used as a substitute for in the deployed environment and to incorporate those data into
detergent. recommendations for military medical personnel.

Keywords: SARS-CoV-2; Covid-19; decontamination; uniform; Materials and Methods
military; detergent; soap; hot water; wash; exposure
RNA Extraction and SARS-Cov-2 Detection
Discarded SARS-CoV-2 specimens were obtained from the
clinical laboratory at the Dwight D. Eisenhower Army Medical
Introduction
Center, Fort Gordon, GA. The presence of viral RNA was de-
The SARS-CoV-2 virus is the causative agent of the disease termined before beginning the study. RNA extraction and pu-
known as COVID-19. The rapid emergence and spread of this rification were performed on the King Fisher Flex Purification
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pathogen has revealed the vulnerability of the U.S. Military to System using the KingFisher Viral/Pathogen II (MVP II) Nu-
infectious disease, and it has underscored the need for devel- cleic Acid Isolation Kit (ThermoFisher Scientific, https://www.
oping modified techniques and procedures for dealing with thermofisher.com/order/catalog/product/A48383). Since RNA
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pathogens in the field. SARS-CoV-2 is a member of the family is an unstable molecule, the detection of viral RNA was used
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Coronaviridae. It is an enveloped virus with a ribonucleic acid as a proxy for the presence of viral particles. The virus was de-
(RNA) genome; a lipid coat surrounds each viral particle. This tected from extracted RNA using real-time polymerase chain
lipid coat protects the viral capsid, a protein shell that con- reaction (PCR) amplification on the 7500 Fast Dx system
tains the viral RNA from the extremes of the environment and using the TaqPath COVID-19 Pooling kit (ThermoFisher Sci-
from attack by the host immune system. Transmission is usu- entific, https://www.thermofisher.com/order/catalog/product/
ally through droplet aerosols impinging on respiratory mucosal A49918) master mix designed to detect the nucleocapsid gene.
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tissue. Transmission via contaminated surfaces is reportedly The PCR procedure was intended to convert viral RNA to
rare. However, previous studies have shown that SARS-CoV-2 DNA and amplify viral DNA to detectable levels. The PCR
can remain stable and infectious on abiotic surfaces for periods cycle at which the DNA levels cross a predetermined threshold
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ranging from hours to days. Significantly, the virus can remain has been termed the cycle-threshold value (CT). There is an
stable on stainless steel and other abiotic surfaces and remain inverse relationship between CT value and concentration of
viable for up to 21 days in a cool environment and for up to viral particles. Lower CT values indicate a higher concentra-
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7 days in a warm climate. Textile studies have demonstrated tion of viral RNA and, consequently, a higher concentration of
that infectious coronaviruses can be removed by washing with viral particles. A CT value of 40 was used as a cut-off for viral
agitation, increased temperature, and detergent. However, ag- detection, with all values equal to or greater than a CT of 40
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itation without temperature and detergent does not seem to being considered undetected.
*Correspondence to charmaine.a.ibarra.mil@health.mil
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1 CPT Charmaine Ibarra, Lyteasha Bass, Eldad Saler, Renae Daniels, SSG Norman Davis, and LTC Michael A. Washington are all affiliated
with Dwight D. Eisenhower Army Medical Center, Fort Gordon, GA.
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