Face masks will be used to prevent pandemic recurrence and outbreaks of mutant SARS-CoV-2 strains until mass immunity is confirmed. The polypropylene (PP) filter is a representative disposable mask material that traps virus-containing bioaerosols, preventing secondary transmission. In this study, a copper thin film (20 nm) was deposited via vacuum coating on a spunbond PP filter surrounding a KF94 face mask to provide additional protection and lower the risk of secondary transmission. Film adhesion was improved using oxygen ion beam pretreatment, resulting in cuprous oxide formation on the PP fiber without structural deformation. The copper-coated mask exhibited filtration efficiencies of 95.1 ± 1.32% and 91.6 ± 0.83% for NaCl and paraffin oil particles, respectively. SARS-CoV-2 inactivation was evaluated by transferring virus-containing media onto the copper-coated PP filters and subsequently adding Vero cells. Infection was verified using real-time polymerase chain reaction and immunochemical staining. Vero cells added after contact with the copper-coated mask did not express the RNA-dependent RNA polymerase and envelope genes of SARS-CoV-2. The SARS-CoV-2 nucleocapsid immunofluorescence results indicated a reduction in the amount of virus of more than 75%. Therefore, copper-coated antiviral PP filters could be key materials in personal protective equipment, as well as in air-conditioning systems.

Strain KIT 00200-70066-1^T was isolated from the sputum of a patient with pulmonary disease. Cells of the strain were Gram-variable, facultatively anaerobic, motile, spore-forming rods and formed colourless to white colonies on tryptic soy agar at 30 °C and pH 7. The pathogenicity of the strain is not known. The strain contained meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall peptidoglycan, MK-7 as the predominant menaquinone, anteiso-C_15 : 0, iso-C_16 : 0 and C_16 : 0 as the major fatty acids and diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and several unknown lipids in the polar lipid profile. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolate belongs to the genus Paenibacillus, sharing the highest levels of sequence similarity with Paenibacillus nanensis MX2-3^T, Paenibacillus agaridevorans DSM 1355^T and Paenibacillus alkaliterrae KSL-134^T (95.4, 95.2 and 94.8 %, respectively), and that it occupied a distinct position within this genus. Combined phylogenetic and phenotypic data supported the conclusion that strain KIT 00200-70066-1^T represents a novel species of the genus Paenibacillus, for which the name Paenibacillus sputi sp. nov. is proposed; the type strain is KIT 00200-70066-1^T (=KCTC 13252^T =DSM 22699^T).