Preparing Viral Transport Media for COVID-19 Testing


November 2020 - Vol.17 No. 11 - Page #24

Note: See the CDC SOP #DSR-052-05, Preparation of Viral Transport Medium, prior to compounding VTM. Be sure to check the CDC website regularly for updates. For more information, see: https://www.cdc.gov/csels/dls/locs/2020/new_sop_for_creating_vtm.html

The test, treat, and track strategy is critical to containing the COVID-19 pandemic, a global health crisis caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The objective of this strategy is to contain the virus by quickly identifying both symptomatic and asymptomatic patients, performing contact tracing, and quarantining patients to reduce transmission.

From the pandemic’s onset, testing has been limited by supply chain problems at all levels. The unprecedented worldwide demand for viral diagnostic testing (ie, polymerase chain reaction [PCR] tests) resulted in critical shortages of key supplies, including flocked nylon swabs for collecting samples and viral transport media (VTM) used for preserving and transporting samples. In response, key companies around the world attempted to quickly scale up manufacturing. These efforts initially stumbled as countries locked down, labor pools fluctuated, and transport systems experienced delays.

In response, the FDA granted emergency use authorizations to allow unapproved medical products (ie, diagnostic tests and related supplies) to enter the market and to relax regulations that allow for expanded production and more timely distribution of already approved products.1 For example, VTM is regulated by the FDA as a medical device because it is used in disease diagnosis. In January 2020, the FDA increased production capacity by allowing manufacturers to sell VTM without submitting a 90-day pre-marketing notification, which includes evidence of equivalence to an existing, legally marketed device. In addition, the FDA issued guidance that temporarily allows Clinical Laboratory Improvement Amendments (CLIA)-certified laboratories to produce VTM for in-house COVID-19 diagnostic testing.2

This article examines the importance of VTM in COVID-19 diagnostic testing and how a department of pharmacy can partner with a hospital laboratory to sustain testing through the manufacturing of VTM.

The Role of VTM in COVID-19 Testing

Viral diagnostic testing consists of three key activities:

  • Sample collection and transport
  • Execution of the test
  • Post-test activities such as result reporting, public health reporting, and contact tracing

Sample collection and transportation is dictated by the type of testing. The most common and reliable COVID-19 diagnostic test is a laboratory-based assay that detects viral nucleic acid through amplification of a SARS-CoV-2 specific sequence, such as reverse transcription PCR (RT-PCR).

SARS-CoV-2 is composed of ribonucleic acid (RNA), which is extremely unstable and degrades easily.3 Thus, storing samples in the wrong environmental conditions can lead to false negative results, as can sample contamination from enzymes or other microorganisms that break down RNA. For this reason, the CDC considers “Proper collection [and storage] of specimens [as] the most important step in the laboratory diagnosis” of COVID-19.2

Sample collection starts with using a sterile swab tipped with a synthetic material (eg, nylon, polyester) to collect secretions from either the patient’s nasopharynx (most common), oropharynx, nasal mid-turbinate, and/or anterior nares (see FIGURE 1). Swabs are ideally “flocked” by electrostatic insertion of pin-like filaments into the swab head, rather than by winding fibers around a shaft, for improved pickup and release of sample. Note that swabs with wooden shafts, cotton tips, and/or containing calcium alginate are not appropriate as they contain genetic material that interferes with diagnostic tests. Only a small subset of available swab inventory is appropriate for viral testing. Collected swabs are then placed in a sterile collection tube and stored at either 2-8°C or -70°C, depending on whether the sample can be tested within 72 hours.2

Within the sterile collection tube is transport media within which the specimen is suspended by breaking the swab at a score point (red line, see FIGURE 2) allowing the head of the swab to fit into the tube. Transport media is designed to be an optimal environment for preserving the viability of a target analyte (ie, virus) during transportation and storage. The gold standard is VTM, also known as universal transport media.2

VTM is preferred as it is a non-hazardous mixture of buffered solutions and antimicrobials that preserves the virus while eliminating contaminant flora that might interfere with testing. It has proven compatibility with a wide variety of clinical tests from PCR to direct antigen testing to culturing, allowing different tests to be run from the same sample.4

Due to VTM shortages, the FDA and CDC have recommended using alternative media, including sterile saline, liquid Amies, and inactivating transport media.2 However, these options do not have the same versatility, stabilizing, and inhibitory properties as VTM. Inactivating transport media is the least desirable as it contains hazardous chemicals that can release toxic cyanide gas when mixed with acids such as bleach, which is a commonly utilized disinfecting agent for eliminating stray contaminant nucleic acids.5,6

Ingredients in VTM

VTM is a device designed to maintain the viability and thus virulence of collected samples. It has been optimized for decades, initially to preserve viability for cultures and later to facilitate nucleic acid-based testing. VTM is composed of fetal bovine serum (FBS), Hanks' Balanced Salt Solution (HBSS), antibiotics and antifungals, as well as phenol red.7 A multitude of variations of the recipe exist and cater to the interactions between sample collection devices (ie, swab) in media solutions, plastic in storage containers, and variability of freeze/thaw cycles.

Ingredients for VTM are commonplace in both clinical and research laboratories. However, within a health-system pharmacy these may be foreign, resulting in concerns from pharmacy colleagues. Thus, the purpose and safety of each ingredient is described below.

  • Fetal Bovine Serum (FBS) is collected from unborn calves that are accidentally discovered after a pregnant cow has been processed.8 This occurrence happens 8% of the time worldwide in animal agricultural settings and results in 2 million fetal cows per year. The blood is prized for its low immunoglobulin (antibodies) content and high concentration of essential components, such as hormones, transport proteins, and growth factor, for cell survival and proliferation.8 Bovine serum albumin is a major component that provides antioxidant, cryoprotectant, and anti-adsorption properties that favor retention of intact virus in solution over lysis and adherence to plastic. Simply put, FBS is an optimal environment to preserve viral host cells and to support viral preservation and amplification, ensuring quality samples for diagnostic testing.

    Commercially, FBS comes in two forms: heat inactivated and not inactivated. Traditionally, most protocols for making VTM include heat inactivation as a necessary step in preparation. This is to rid the serum of any complement proteins that inadvertently eliminate foreign organisms (eg, viruses). The utility of heat inactivation is debated as some experts consider the complement factors present to be negligible. With lack of definitive evidence, heat inactivation is a conservative approach, especially given the low cost and technical skill needed.

    Pharmacy colleagues may be uncomfortable handling FBS as it is a serum-supplement. However, note that FBS does not present any health hazards, physical hazards, or environmental hazards. Additionally, no hazard statements or precautionary statements (ie, prevention, response, storage, disposal) are applicable to FBS.9

  • Hanks' Balanced Salt Solution (HBSS) provides an isotonic solution to liquid media that contributes to the physiological requirements necessary for cell and viral stability.7 Variations of HBSS may include calcium, magnesium, and/or phenol red. HBSS is non-hazardous to humans.10
  • Antibiotics and antifungals (ie, gentamicin and amphotericin B) keep liquid media free of contaminants. Bacteria and fungi from the respiratory tract and other sites can disrupt viral particles’ viability and/or degrade DNA and RNA if allowed to proliferate.
  • Phenol red is a commonly used pH indicator in cell biology labs. It is a weak acid that provides a color change from yellow (pH 6.8 or below) to fuchsia (pH 8.2 or above) (see FIGURE 3). It can provide an assessment for the correct compounding parameters, indicate that the solution pH is optimal, and whether the media (as initially compounded) has been subsequently contaminated or exposed to air via a loose cap.11 The use of phenol red may be omitted if a laboratory or pharmacy has proper pH-testing equipment, but in clinical practice a visual check is more easily done on a per-sample and per-batch basis.
     

See the SIDEBAR for a case study of VTM preparation.

Conclusion

UIHC has been able to meet the increased demand for COVID-19 testing without interruption due in part to the onsite production of VTM. Pharmacy departments, in collaboration with CLIA-certified laboratories, are well-positioned to expedite onsite VTM production when commercial VTM is unavailable. Without onsite VTM production, UIHC’s testing capacity would have been exceeded, resulting in substantial testing delays. As the global supply chain of VTM normalizes, onsite production by pharmacy will no longer be relied upon as a primary source at UIHC. However, in today’s unpredictable world, hospitals must have a back-up plan in place that can be quickly activated and scaled when demand for testing increases and supply chain failures occur.

References

  1. FDA Combating COVID-19 with Medical Devices. Food and Drug Administration. https://www.fda.gov/media/136702/download. Accessed August 2, 2020.
  2. Interim Guidelines for Collecting, Handling, and Testing Clinical Specimens for COVID-19. Centers for Disease Control and Prevention website. https://www.cdc.gov/coronavirus/2019-nCoV/lab/guidelines-clinical-specimens.html. Accessed August 1, 2020.
  3. FDA Coronavirus Testing Basics. Food and Drug Administration. Published July 3, 2020. https://www.fda.gov/consumers/consumer-updates/coronavirus-testing-basics. Accessed August 1, 2020.
  4. Universal Transport Medium for Virus and Bacteria. COPAN. https://products.copangroup.com/index.php/products/clinical/utm. Accessed August 5, 2020.
  5. Laboratory biorisk management for laboratories handling human specimens suspected or confirmed to contain novel coronavirus. World Health Organization. Published February 19, 2013. https://www.who.int/csr/disease/coronavirus_infections/Biosafety_InterimRecommendations_NovelCoronavirus_19Feb13.pdf. Accessed August 12, 2020.
  6. Testing Supply Substitution Strategies. U.S. Food and Drug Administration. Published July 23, 2020. https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medical-devices/faqs-testing-sars-cov-2. Accessed 8/3/20. Accessed July 29, 2020.
  7. Johnson FB. Transport of viral specimens. Clin Microbiol Rev. 1990;3(2):120-131.
  8. Van der valk J, Bieback K, Buta C, et al. Fetal Bovine Serum (FBS): Past - Present - Future. ALTEX. 2018;35(1):99-118.
  9. Safety Data Sheet – Fetal Bovine Serum. ThermoFisher Scientific. Published March 21, 2012. http://tools.thermofisher.com/content/sfs/msds/2012/10439001_MTR-APLT_BE.pdf. Accessed August 2, 2020.
  10. Safety Data Sheet – HBSS. ThermoFisher Scientific. Published July 9, 201510.1073/pnas.83.8.2496. https://www.thermofisher.com/document-connect/document-connect.html?url=https%3A%2F%2Fassets.thermofisher.com%2FTFS-Assets%2FLSG%2FSDS%2F14060040_MTR-NALT_EN.pdf&title=MTQwNjAwNDA=. Accessed August 2, 2020.
  11. Berthois Y, Katzenellenbogen JA, Katzenellenbogen BS. Phenol red in tissue culture media is a weak estrogen: implications concerning the study of estrogen-responsive cells in culture. Proc Natl Acad Sci USA. 1986;83(8):2496-2500.
  12. Enforcement Policy for Viral Transport Media During the Coronavirus Disease 2019 (COVID19) Public Health Emergency. Guidance for Commercial Manufacturers, Clinical Laboratories, and Food and Drug Administration Staff. Food and Drug Administration. Published July 2020.
  13. Preparation of Viral Transport Media – SOP# DSR-052-04. Centers for Disease Control and Prevention. Published July 23, 2020. https://www.cdc.gov/coronavirus/2019-ncov/downloads/Viral-Transport-Medium.pdf. Accessed August 12, 2020.
  14. Gibco fetal bovine serum (FBS): Frequently asked questions. ThermoFisher Scientific. Published September 7, 2014. https://www.thermofisher.com/content/dam/LifeTech/global/life-sciences/CellCultureandTransfection/pdfs/Gibco-FBS-FAQs-Flyer-Global-FLR.pdf. Accessed August 3, 2020.
  15. CFR - Code of Federal Regulations Title 21. US Food and Drug Administration. Published April 1, 2019. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=809.10. Accessed August 5, 2020.

Felix Lam, PharmD, MBA, BCPS, is the pediatric pharmacy operations manager for University of Iowa Health Care (UIHC) in Iowa City, Iowa. He earned his Doctor of Pharmacy from the University of North Carolina Eshelman School of Pharmacy and his MBA with an emphasis on health care management from the Johns Hopkins Carey Business School while completing a combined PGY1/PGY2 in health-system pharmacy administration at The Johns Hopkins Hospital.

Majd Moubarak, BS, is a pharmacy technician for the University of Iowa Stead Family Children’s Hospital in Iowa City, Iowa. She completed her Bachelor of Science in plant biology from the University of Iowa. When not caring for patients at the hospital, she continues to pursue her research interest in plant regeneration. She is actively pursuing national pharmacy technician certification.

Jonathan Wilson, PharmD, MHA, BCPS, BCSCP, is an adult pharmacy operations manager for the University of Iowa Hospitals and Clinics in Iowa City, Iowa. He earned his Doctor of Pharmacy degree from the University of Minnesota College of Pharmacy. Jonathan completed his MHA at the University of Iowa College of Public Health while completing a combined PGY1/PGY2 in Health-System Pharmacy Administration at the University of Iowa Hospitals and Clinics.

Bradley Ford, MD, PhD, is the medical director of the clinical microbiology laboratory for the University of Iowa Hospital and Clinics. He earned his Doctor of Medicine and Doctor of Philosophy from Stony Brook School of Medicine. His research focuses on optimizing clinical diagnostics using a variety of next-generation microbiology platforms.


SIDEBAR

Case Study: University of Iowa Health Care

The University of Iowa Health Care (UIHC) is a non-profit, academic medical system that includes 811 beds within two tertiary care hospitals: UI Hospital and Clinics and UI Stead Family Children’s Hospital. Due to the national shortage of viral transport media (VTM), UIHC pursued onsite preparation of VTM for use within the main campus hospitals. In order to meet significant demand (ie, over 500 tests per day), the UIHC pathology department collaborated with the pharmacy department to compound VTM given the availability of primary engineering controls (PECs) within pharmacy and certified pharmacy technicians competent in aseptic manipulations for preparation of sterile products. Furthermore, pathology contributed extensive knowledge of laboratory reagents and VTM validation while pharmacy provided expertise to scale preparation of VTM.

The collaboration resulted in expedited development of procurement and preparation processes to meet the testing demand of the system on short notice. UIHC utilized the CDC and Indiana University Health Clinical Virology Laboratory standard operating procedures on the preparation of VTM to prepare and validate over 2800 units (3 mL aliquots) of VTM within a 1 week time period from project initiation (see FIGURE 4). Validated VTM continues to be used for diagnostic testing of viral infections, including COVID-19.

See the APPENDIX for UIHC’s VTM Master Formulation Record.

Sourcing Supplies

Procurement

The FDA recommends that laboratories certified under CLIA follow the CDC’s standard operating procedure entitled Preparation of Viral Transport Media when compounding and validating VTM during a supply shortage.12 Pharmacy departments collaborating with CLIA-certified laboratories should follow preparation procedures developed utilizing the CDC standard operating procedure prior to laboratory validation of the VTM.

Reagents

Reagents used in the compounding of VTM may be obtained from a biomedical research supplier or directly from the hospital laboratory in facilities or systems that have this capability. Purchasing reagents from a biomedical research supplier affiliated with your institution provides the benefit of discounted pricing from large volume contracting with vendors. Alternatively, reagents can be purchased directly from a biotechnology reagent producing company serving clinical and research-laboratory clients, and perhaps forsake the benefits of contracted pricing and onsite availability.

Special Considerations

Supplies

Common supplies listed in recipes include serological pipettors/pipet-aids, individually wrapped sterile pipets, sterile conical tubes, filter assemblies, labels, and disinfectants. Supplies can be obtained from a biomedical research supplier or directly from the manufacturer, when not available from hospital inventory or the pathology department.

Special Considerations

Equipment & Environmental Controls

Equipment needed to prepare and aliquot VTM is readily available in a laboratory setting (eg, vacuum pump, water bath, refrigerator, incubator, sterile pipette). However, access to an ISO Class 5 environment for preparation and aliquoting of VTM remains a limiting factor for preparation. VTM can be aseptically prepared in a PEC in the pharmacy.

Special Considerations

The pathology department assists with quality assurance checks, which include culture-based sterility tests that may be performed in the microbiology laboratory conducting COVID-19 testing. Refer to the CDC Standard Operating Procedure for Sterility and Quality Checks.13

Expiration Dating

See TABLE 1 for information about expiration dating. The CDC recommends a 1 year expiration date from preparation of VTM bulk product and aliquots while Indiana University Health Clinical Virology Laboratory assigns the bulk product an expiration date of 1 month after first use and aliquots 1 year after preparation.13 The FDA recommends that shelf life, stability, and limitations follow the CDC standard operating procedure guidelines for proper labeling of VTM, in which case VTM is viable up to 1 year after manufacturing.13 UIHC assigned VTM bulk product a conservative 30-day expiration date from the time of preparation. Aliquots received the expiration dating based on the bulk product used for preparation.

Note that USP <797> beyond-use dating does not apply to preparation of VTM as it is a diagnostic device not intended for administration to patients.

Staffing Considerations

See TABLE 2 for information about staffing time required for the steps in VTM preparation.

 

APPENDIX

Master Formulation Record

Official Name: Viral Transport Medium—Fetal Bovine Serum 2%,
Gentamicin 100 µg/mL, Amphotericin B 0.5 µg/mL

Form: Solution

Auxiliary Labeling:

**For transport of specimens only**

**Not to be taken internally**

REFRIGERATE

DO NOT FREEZE

Batch Volume: 512 mL

Dispense Product: 3 mL aliquots in conical tubes (~160 units)

Expiration Date for Bulk Product: 30 days (bulk product expiration date given to aliquots)

Storage: Refrigerated, 2-8°C

 

Description of Ingredients

Method of Preparation

Final Product Description: Pink Solution

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