Evaluation of steam heat as a decontamination approach for SARS-CoV-2 when applied to common transit-related materials

AIMS

The purpose of this study was to evaluate the efficacy of steam heat for inactivation of SARS-CoV-2 when applied to materials common in mass transit installations.

METHODS AND RESULTS

SARS CoV-2 (USA-WA1/2020) was resuspended in either cell culture media or synthetic saliva, inoculated (∼1 × 106 TCID50) onto porous and nonporous materials and subjected to steam inactivation efficacy tests as either wet or dried droplets. The inoculated test materials were exposed to steam heat ranging from 70°C to 90°C. The amount of infectious SARS-CoV-2 remaining after various exposure durations ranging from 1 to 60 s was assessed. Higher steam heat application resulted in higher inactivation rates at short contact times. Steam applied at 1-inch distance (∼90°C at the surface) resulted in complete inactivation for dry inoculum within 2 s of exposure (excluding two outliers of 19 test samples at the 5-s duration) and within 2-30 s of exposure for wet droplets. Increasing the distance to 2 inches (∼70°C) also increased the exposure time required to achieve complete inactivation to 15 or 30 s for materials inoculated with saliva or cell culture media, respectively.

CONCLUSIONS

Steam heat can provide high levels of decontamination (>3 log reduction) for transit-related materials contaminated with SARS-CoV-2 using a commercially available steam generator with a manageable exposure time of 2-5 s.

Decontamination efficacy of common liquid disinfectants against non-spore-forming biological agents in soil matrices

AIMS

The purpose of this study was to evaluate decontamination efficacy, within three soil types, against Yersinia pestis, Burkholderia pseudomallei, and the Venezuelan Equine Encephalitis virus (VEEV).

METHODS AND RESULTS

One of three liquid disinfectants (dilute bleach, Virkon-S or Klozur One) was added to three soil types (sand, loam, or clay) and allowed contact for four pre-spike durations: 0, 15, 30 and 60 min. Y. pestis, B. pseudomallei, or VEEV was then spiked into the soil (10 microliters or approx. 1 × 107  CFU or PFU into 1 g soil) and decontamination efficacy assessed at post-spike contact times of 10 or 60 min at ambient environmental conditions. Across all soil types, sandy soil resulted in the least quenching to all three disinfectants tested as shown by sustained decontamination efficacy across all pre-spike and post-spike timepoints. Clay and loam soil types exhibited quenching effects on the hypochlorite and peroxygen based disinfectants (dilute bleach and Virkon S) and in general resulted in decreased efficacy with increased pre-spike contact time. The sodium persulfate (Klozur One) performance was the most consistent across all soil types and pre-spike contact times, resulting in greater efficacy with increased post-spike time.

CONCLUSIONS

Liquid disinfectants can provide high levels of decontamination in soil for both viral and non-spore-forming bacterial select agents. Hypochlorite and peroxygen based disinfectants used in soils containing higher organic content (loam or clay) may require extended contact times or re-application of liquid disinfectant, in as little as 15 min of application, to achieve a 6-log reduction.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results provide information for the performance of three disinfectants in soil against non-spore-forming select agents. These data may aid response decision makers following a biological contamination incident by informing the selection of disinfectant as well as the re-application time to achieve effective site remediation.

Evaluation of environmental conditions as a decontamination approach for SARS-CoV-2 when applied to common library, archive and museum-related materials

AIMS

The purpose of this study was to evaluate the effects of ambient or altered environmental conditions on the inactivation of SARS-CoV-2 applied to materials common in libraries, archives and museums.

METHODS AND RESULTS

Porous and non-porous materials (e.g. paper, plastic protective book cover) were inoculated with approximately 1 × 105 TCID50 SARS CoV-2 (USA-WA1/2020), dried, placed within test chamber in either a stacked or unstacked configuration, and exposed to environmental conditions ranging from 4 to 29°C at 40 ± 10% relative humidity. The amount of infectious SARS-CoV-2 was then assessed at various timepoints from 0 to 10 days. Ambient conditions resulted in varying inactivation rates per material type. Virus inactivation rate decreased when materials were stacked or at colder temperatures. Virus inactivation rate increased when materials were unstacked or at warmer temperatures.

CONCLUSIONS

SARS-CoV-2 at ambient conditions resulted in the inactivation of virus below limit of quantitation (LOQ) for all materials by Day 8. Warmer temperatures, for a subset of materials, increased SARS-CoV-2 inactivation, and all were

SIGNIFICANCE AND IMPACT OF THE STUDY

These results provide information for the library, archives and museum community regarding the inactivation of SARS-CoV-2, showing that inactivation is possible using prescribed environmental conditions and is a potential method of decontamination for items not compatible with common liquid disinfectants.

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Key Words

• COVID-19
• SARS-CoV-2
• archives
• books
• decontamination
• inactivation
• libraries
• museums
• paper
• persistence
• plastic

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MESH Headings

• COVID-19/prevention & control
• Decontamination/methods
• Humans
• Museums
• SARS-CoV-2
• Virus Inactivation

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Grants

• ODIS-246644-ODIS-20 Institute of Museum and Library Services
• CON00031948 OCLC
• Institute of Museum and Library Services
• OCLC

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Affiliation(s)

William R. Richter Battelle Memorial InstituteColumbusOHUSA
Michelle M. Sunderman Battelle Memorial InstituteColumbusOHUSA
Tom O. Mera Battelle Memorial InstituteColumbusOHUSA
Kim A. O'Brien Battelle Memorial InstituteColumbusOHUSA
Kendra Morgan OCLCDublinOHUSA
Sharon Streams OCLCDublinOHUSA

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Evaluation of altered environmental conditions as a decontamination approach for nonspore-forming biological agents

AIMS

The purpose of this study was to evaluate the effects of altered environmental conditions on the persistence of Francisella tularensis bacteria and Venezuelan equine encephalitis virus (VEEV), on two material types.

METHODS AND RESULTS

Francisella tularensis (F.t.) and VEEV were inoculated (c. 1 × 108 colony-forming units or PFU), dried onto porous and nonporous fomites (glass and paper), and exposed to combinations of altered environmental conditions ranging from 22 to 60°C and 30 to 75% relative humidity (RH). Viability of test organism was assessed after contact times ranging from 30 min to 10 days. Inactivation rates of F.t. and VEEV increased as both temperature and/or RH were increased. Greater efficacy was observed for paper as compared to glass for both test organisms.

CONCLUSIONS

The use of elevated temperature and RH increased rate of inactivation for both organisms and greater than six log reduction was accomplished in as little as 6 h by elevating temperature to approximately 60°C.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results provide information for inactivation of nonspore-forming select agents using elevated temperature and humidity which may aid incident commanders following a biological contamination incident by providing alternative methods for remediation.