FEMALE SPEAKER: Welcome to Mayo Clinic COVID-19 Expert Insights and Strategies. The following activity is supported in part by an independent medical education grant from Pfizer Inc and is in accordance with ACCME guidelines.

JEFF NESBITT: Hi. My name is Jeff Nesbitt from Mayo Clinic Occupational Safety. Today, I will be talking about COVID-19 respiratory protection updates. Thank you for your time in reviewing this presentation.

At the end of this section, participants will be able to recall where to find guidance for respirator use during COVID-19, when to wear a respirator, and when to extend use or reuse of a respirator. At Mayo Clinic, we use a multidisciplinary team to build expert clinical guidance and to make risk-based decisions. Our guidance on risk and controls for aerosol--generating procedures is available online from the map Ask Mayo Expert application. The CDC provides infection prevention and control recommendations and resources in the links provided on the slide.

Current CDC data suggests that close range aerosol transmission by droplet and inhalation and contact followed by self delivery to the eyes, nose, or mouth are likely roots of transmission. Long range aerosol transmission, such as seen with measles has not been a feature of SARS-CoV-2 and the resulting disease termed COVID-19. Face masks are routinely used for the care of patients with COVID-19. The use of respirators are prioritized by activity type. Face masks are replaced with respirators during aerosol-generating procedures as discussed in the previous slide.

Surge capacity is a useful framework outlined by the CDC to prioritize respirator usage based on availability during the COVID-19 pandemic where conventional usage of respirators is not practical. This framework consists of three levels-- conventional, contingency, and crisis capacities. Contingency capacity would be considered a time of expected shortage or extended use of disposable N95 respirators would be allowed.

Extended use refers to the practice of wearing the same N95 respirator for repeated close contact encounters with multiple patients infected with the same pathogen without removing the respirator between patient encounters. The maximum recommended period is 8 to 12 hours. Crisis capacity would be considered a time of known shortages where reuse of the N95 respirators may become necessary.

Reuse refers to the practice of using the same respirator for multiple encounters with patients but removing it after each encounter. It is stored in between encounters to be put on again prior to the next encounter with the patient. If no manufacturer guidance is available, limit the number of reuses to no more than five per respirator.

N95 respirators may be worn, saved, and reused if appropriate precautions are taken to don and doff properly and store the respirator safely between reuses. Reuse is recommended only if a full face shield is worn to protect the respirator during high risk activities. A link to the guidance document within the Ask Mayo Expert application has been provided on this slide. Reuse is not recommended if the respirator is visibly soiled or damaged or cannot not pass the user seal check.

The next section focuses on reprocessing of N95 respirators during times of anticipated shortages. The following learning objectives will be covered-- identify when it is appropriate to reprocess N95 respirators, recall quality and performance requirements for reprocessed N95 respirators, identify suitable reprocessing methods and quality indicators, identify quality checks and precautionary measures that health care providers should take prior use of reprocessed N95 respirators. N95 filtering face piece respirators are disposable protective devices.

CDC indicates that N95s should be reprocessed only when there is a shortage of new respirators. COVID-19 has created shortages of respirators in some areas, leading to the evaluation of suitable reprocessing methods. For N95 respirators to be successfully reprocessed, filtration must continue to meet the same specification as new respirators.

The product must continue to provide adequate fit and be safe for the user. Chemical residues or remaining viable COVID-19 deposits would be examples of unsafe reprocessing. A number of methods for reprocessing N95 respirators has been discussed in the literature and by the media during the COVID-19 pandemic.

In April of 2020, three methods were designated by CDC and N95 manufacturers as having the most promise and available scientific data to support their use in reprocessing respirators-- ultraviolet germicidal irradiation, moist heat, and vaporized hydrogen peroxide reprocessing. UVGI is a promising method often used for small scale reprocessing. No harmful residual chemicals are left on the N95 after radiation with UV, and filtration efficiency has been found adequate after approximately three cycles of irradiation.

Disinfection efficiency is dependent on dose, and the following limitations have been noted. UV lamps differ in intensity, so the time of disinfection varies by lamp. Disinfection efficiency decreases with distance from the UV resource. Shadows in areas not able to be exposed to UV decrease effectiveness, and UV radiation can reduce the elasticity of N95 respirator straps over time.

Moist heat is best suited to small scale reprocessing. N95 respirator fit and filtration efficiency have been found acceptable after three cycles of reprocessing. This method has a very limited amount of data available to support its use at this time. Vaporized hydrogen peroxide reprocessing has been done on a large scale which may include thousands of N95s during a single run.

N95 respirators have been reported to be reprocessed up to 50 times with VHP without negatively affecting the fit or filtration of the respirator. VHP has been demonstrated to achieve a six log reduction of biological organisms, including COVID-19. VHP is an environmentally friendly process where hydrogen peroxide breaks down rapidly after the cycle is completed to oxygen and water, leaving no hazardous chemical residues or odor on the restaurant. FDA has granted numerous companies emergency use authorization for the use of VHP to reprocess N95 respirators.

The photo on this slide depicts an actual VHP reprocessing module. In the photo, you can see how the N95 respirators are open prior to reprocessing to better expose all surfaces to adequate vapor concentration. As part of Mayo clinic's VHP reprocessing quality assurance program, chemical and biological indicators are utilized during each reprocessing run. Chemical indicators ensure that an adequate concentration of VHP is provided and maintained through the reprocessing run. Biological indicators ensure adequate organism kill is achieved. Biological indicators are read after seven days to determine if a six log reduction in viable microorganisms has been achieved.

To ensure that all respirators are free from damage, soiling, or other defect, each N95 is inspected prior to and after reprocessing. Any product with a noted defect is discarded. A representative sample of respirators in each load are quantitatively fit tested to confirm adequate fit has been maintained.

A health care provider who is given a reprocessed N95 should do a final assessment prior to use, which includes washing hands with soap and water or an alcohol--based hand sanitizer and after handling an N95 respirator. Visually inspect the respirator to look for any visible defects such as loose straps, worn nose bridge, damage, or soiling. If any damage to the N95 respirator is visible or successful user seal check cannot be performed, discard the N95 respirator. Never use an N95 respirator, new or reprocessed, if the user seal check is unsuccessful.

In summary, it may be necessary to reprocess N95 respirators when there's a shortage of new respirators. UGI, moist heat, and vaporized hydrogen peroxide reprocessing methods were designated by the CDC and N95 respirators manufacturers as having the most promise and available scientific data to support their use in reprocessing. VHP has been demonstrated to achieve a six log reduction in microorganisms, including SARS-CoV-2 virus.

A reprocessing cycle is successful when the chemical and biological indicators demonstrate that VHP was distributed to all areas of the reprocessing room. Quality checks and precautionary measures taken as part of the reprocessing procedure are essential for the safety of patients and staff. Thank you.