SARS-CoV-2 Inactivation on Hard Non-porous Airplane Cabin Material Surfaces was Limited After Exposure to Far UV-C (222 nm) Radiation.

AIMS: To test the efficacy of 222 nm Far UV-C for surface disinfection of SARS-CoV-2 on inanimate surfaces from airplane cabins. METHODS AND RESULTS: Two far ultraviolet (UV-C) irradiation light systems were evaluated for disinfection of SARS-CoV-2. Materials used for carriers (test surfaces) included polished stainless steel and used airplane materials including seatbelt latches, window dust covers, sidewall laminates, and tray tables. CONCLUSIONS: While demonstrating reasonable efficacy under some experimental conditions, the data indicated that 222 nm Far UV-C disinfection alone does not reliably provide a 3 log10 or 99.9% reduction of SARS-CoV-2 on inanimate surfaces from an airplane cabin. An Ushio (Cypress, CA) 1.7" x 2.3" Care222® 12W 222nm BI lamp module tested in triplicate at a low (⁓ 1.5 mJ cm-2), medium (⁓ 3.0 mJ cm-2), and high (⁓ 6 to 9 mJ cm-2) fluence did not provide a ≥ 3 log10 or 99.9% reduction of SARS-CoV-2. The reduction of SARS-CoV-2 was greatest on stainless steel. The result was a log10 reduction of 2.83, 1.33, 2.58, and 2.21 logs for virus samples containing saline, saline with 2.5 mg BSA, saline with 0.25 mg BSA, and artificial saliva respectively at a dosage of 5 to 9 mJ cm-2. The log10 reduction of SARS-CoV-2 in saline with 2.5 mg bovine serum albumin was lowest with 1.33 for stainless steel, 0.93 for belt latch, and 0.61 for tray table at a dosage of 5 to 6 mJ cm-2.The second UV lighting system tested was a prototype mobile wand with a built-in short-pass filtered krypton-chloride cylindrical lamp. One pass of the wand over a tray holding carriers inoculated with SARS-CoV-2 in artificial saliva at a rate of approximately 1 foot (1') per second (sec) exposed the carriers to 7.3 mJ cm-2. The log10 reductions determined for the single pass were 2.97, 3.75, 1.78, 1.91, and 1.28 logs for stainless steel, belt latch, dust cover, sidewall, and tray table respectively. Two passes of the wand generated 17.2 mJ cm-2 and resulted in log10 reductions of 4.04, 3.74, 4.24, 3.68, and 1.66 logs for stainless steel, belt latch, dust cover, sidewall, and tray table respectively. The combination of higher fluence from multiple passes of the wand, the close proximity (10 cm wand to the carrier), the exposure to elevated temperatures up to 35°C, and ozone from the bulb being blown directly onto the carriers contributed to effective viral inactivation on all surfaces except the airplane tray table. The impact of temperature and ozone on viral inactivation should be determined for future testing of the 222 nm UV-C wand.

Computational fluid dynamics modeling of cough transport in an aircraft cabin.

To characterize the transport of respiratory pathogens during commercial air travel, Computational Fluid Dynamics simulations were performed to track particles expelled by coughing by a passenger assigned to different seats on a Boeing 737 aircraft. Simulation data were post-processed to calculate the amounts of particles inhaled by nearby passengers. Different airflow rates were used, as well as different initial conditions to account for random fluctuations of the flow field. Overall, 80% of the particles were removed from the cabin in 1.3-2.6 min, depending on conditions, and 95% of the particles were removed in 2.4-4.6 min. Reducing airflow increased particle dispersion throughout the cabin but did not increase the highest exposure of nearby passengers. The highest exposure was 0.3% of the nonvolatile mass expelled by the cough, and the median exposure for seats within 3 feet of the cough discharge was 0.1%, which was in line with recent experimental testing.

Probability and estimated risk of SARS-CoV-2 transmission in the air travel system.

BACKGROUND: As an emerging virus, SARS-CoV-2 and the risk of transmission during air travel is of high interest. This paper is a retrospective estimate of the probability of an infectious passenger in the air travel system transmitting the SARS-CoV-2 virus to a fellow passenger. METHODS: Literature was reviewed from May-September 2020 to identify COVID-19 cases related to air travel. The studies were limited to publicly available literature for passengers; studies of flight crews were not reviewed. A novel quantitative approach was developed to estimate air travel transmission risk that considers secondary cases, the overall passenger population, and correction factors for asymptomatic transmission and underreporting. RESULTS: There were at least 2866 index infectious passengers documented to have passed through the air travel system in a 1.4 billion passenger population. Using correction factors, the global risk of transmission during air travel is estimated at 1:1.7 million; acknowledging that assumptions exist around case detection rate and mass screenings. Uncertainty in the correction factors and a 95% credible interval indicate risk ranges from 1 case for every 712,000 travelers to 1 case for every 8 million travelers. CONCLUSION: The risk of COVID-19 transmission on an aircraft is low, even with infectious persons onboard.

DNA profiling by capillary array electrophoresis with non-covalent fluorescent labeling.

Increasing need for large-scale DNA profiling necessitated the development of automated electrophoresis based methods enabling rapid, high performance analysis of nucleic acids in a wide molecular-mass range. In this paper, we report on the adaptation of a commercial 96-capillary array electrophoresis (CAE) instrument for high-throughput DNA fragment analysis and the evaluation of the effects of different non-covalent DNA staining dyes on separation efficiency. The applicability of different color internal fluorescent standards is shown with mathematical spectral overlap correction algorithms. Large-scale quality control assessment of oligonucleotide probes using non-covalent fluorophore labeling is also demonstrated. The method requires small sample amounts, offers automation and quantification capabilities to accommodate modern biotechnology industry needs.

Large-scale carbohydrate analysis by capillary array electrophoresis: part 1. Separation and scale-up.

A 96-capillary array electrophoresis (CAE) instrument has been adapted for large-scale mono- and oligosaccharide analysis and characterization. Operational protocols and data processing tools have been developed to optimize the CAE system for this application. Effects of different additives to the running buffer on efficiency and capillary-to-capillary performance reproducibility have been studied.

Large-scale carbohydrate analysis by capillary array electrophoresis: part 2. Data normalization and quantification.

Automated 96-capillary array electrophoresis (CAE) methodology described in the first part of the present work offered large-scale high-performance profiling of oligo- and monosaccharides to fulfill the needs of bioindustrial laboratories. Sensitivity at low nanomolar concentration, good resolving power and reliability achieved in the experiments is invaluable for monitoring reaction products from enzymatic polysaccharide digestion with numerous applications in agricultural, chemical and food industries. In addition to optimization of mono- and oligosaccharide separations in CAE system and necessary operational protocol modifications, capillary-to-capillary and run-to-run variation in migration time and signal intensity necessitated development of data normalization tools. Internal fluorescent standards have been incorporated into the analysis aiding migration time normalization and CAE trace alignment. Data processing, visualization, and programming tools have been developed along with quantification approaches.