Finding an Alternative Approach when Critical Medical Supplies Are in Short Supply during the COVID-19 Pandemic

The COVID-19 pandemic has created shortages of various medical supplies, in addition to personal protective equipment that threaten to delay or prevent the timely initiation of important studies At the height of the pandemic, researchers at the National Institute of Allergy and Infectious Diseases, Integrated Research Facility were working to develop a nonhuman primate (NHP) model for COVID-19 Computed tomography (CT) of the lungs is a critical component of these studies This procedure involves placing intubated NHPs on a ventilator circuit to allow a breath hold to be performed on the animal during the chest CT A pediatric-sized heat moisture exchanger (viral/bacterial) filter is placed on the endotracheal tube to prevent contamination of the ventilator circuit on the anesthesia machine When planning and scheduling these studies, we learned the filters were not available or were backordered depending on the vendor The filters are normally used once and discarded, but we quickly realized the supply would run out if we did not receive a new shipment A plan was devised to reuse filters on noninfected animals or sterilize filters using ethylene oxide (EtO) gas after each use on virus-exposed animals before reusing the same filter on the same animal After sterilization, a portable gas leak detector was used to check each filter for residual EtO The first set of filters requiring gas sterilization still had low levels of residual EtO (2 6-2 9 ppm) after overnight aeration in the BSC An additional 24-h aeration period brought the EtO level to 0 0 ppm After each gas sterilization, the integrity of the filter was evaluated with a handheld particle counter capable of counting particles as small as 0 3 μm There were no particles detected which indicated the filtration integrity remained intact for particles ≥ 0 3 μm We describe the procedures we employed to sterilize these filters and determine if they would be safe and effective for reuse These procedural modifications allowed critically important research to find an animal model for COVID-19 to continue without compromising animal welfare