Coating with Hypertonic Saline Improves Virus Protection of Filtering Facepiece Manyfold-Benefit of Salt Impregnation in Times of Pandemic.

Recently, as is evident with the COVID-19 pandemic, virus-containing aerosols can rapidly spread worldwide. As a consequence, filtering facepieces (FFP) are essential tools to protect against airborne viral particles. Incorrect donning and doffing of masks and a lack of hand-hygiene cause contagion by the wearers' own hands. This study aimed to prove that hypertonic saline effectively reduces the infectious viral load on treated masks. Therefore, a hypertonic salt solution´s protective effect on surgical masks was investigated, specifically analyzing the infectivity of aerosolized Alphacoronavirus 1 in pigs (Transmissible Gastroenteritis Virus (TGEV)). Uncoated and hypertonic salt pre-coated FFPs were sprayed with TGEV. After drying, a defined part of the mask was rinsed with the medium, and the eluent was used for the infection of a porcine testicular cell line. Additionally, airborne microorganisms´ long-term infectivity of sodium-chloride in phosphate-buffered saline comprising 5% saccharose was investigated. In the results from an initial Median Tissue Culture Infectious Dose, infection rate of TGEV was minimally reduced by untreated FFP. In contrast, this could be reduced by a factor of 104 if FFPs were treated with hypertonic salt solutions. Airborne pathogens did not contaminate the growth medium if salt concentrations exceeded 5%. We conclude that hypertonic saline is a vital tool for anti-virus protection, exponentially improving the impact of FFPs.

Improved protection of filtering facepiece through inactivation of pathogens by hypertonic salt solutions - A possible COVID-19 prevention device.

The filtering facepiece operates through filtration without the ability to kill the viruses. If the filtration might be combined with antiviral agents simultaneously in the masks, this would be much more efficient during the use of these masks and against cross-infection after being discarded. For centuries, sodium chloride (NaCl) contributes to inhibiting pathogens on various occasions. If aerosol with infectious agents reaches the filtering face-piecé surface of the filtering face-piece, coated with hypertonic saline, they become attracted by hygroscopic salt crystals. Proteins and nucleic acids lose their structural integrity and become inactivated concerning their infectious properties. We provide further evidence for cell growth inhibition with hypertonic saline in yeast cells comprising a defending cell wall. Proliferation was inhibited in a concentration-dependent manner, i.e., above 50 g/L, yeast cell proliferation was completely blocked. At a NaCl concentration of 100 g/L, even decomposition of the original inoculated organisms was observed. Therefore, we conclude that hypertonic saline- coated filtering facepiece might strongly reduce the numbers of infectious particles on their surfaces and thus protect mask carriers efficiently from infections.