Validation of Air Sampling Methods Inside the Heating, Ventilation, and Air Conditioning (HVAC) Inside Student Dorms Using an Improved qRT-PCR Analysis Method

SINAN SOUSAN, Marina Boatman, Lauren Johansen, Ming Fan, Rachel Roper, Department of Public Health, East Carolina University

     Abstract Number: 703
     Working Group: Bioaerosols

Abstract
The COVID-19 pandemic forced institutions to adopt remote learning methods that presented obstacles and minimized social interactions weakening the learning process and creating mental health problems. Due to these events, these institutions reopened face-to-face learning and enforced mitigation strategies to limit the spread of the disease and sustain on-campus activities. This work validated a previously established method to detect the SARS-CoV-2 virus responsible for COVID-19 disease inside the Heating, Ventilation, and Air Conditioning (HVAC) system of student dorms. This was accomplished by performing air sampling using different methods and media types combined with qRT-PCR analysis inside two environments during the Fall semester. The first was the unknown environment, without the knowledge of a COVID-19 case in the dorm, by sampling air from the HVAC system that represents the return air for the entire dorm. The second was the known environment to compare the different methods and media types used by sampling air directly from the HVAC system of a suite occupied by a COVID-19 positive student. The air sampling methods were performed using Filter Cassettes, Button Sampler, BioSampler, and AerosolSense Sampler. For the Button Sampler, four media types for the 25-mm filter were used with different pore sizes of 5 µm, 3 µm, 3 µm (gelatin), and 1.2 µm. The SARS-CoV-2 positive air samples were compared with the positive samples collected by campus track tracing methods using PCR testing on saliva and nasopharyngeal samples. The results show a detection rate of 17% in the unknown environment using the Button sampler (25-5) and a 65% detection rate in the known dorm. However, the detection rate was different by method, with 25% for Filter Cassettes, 39% for Button Sampler with 25-5, 19% for Button Sampler with 25-1.2, 17% for Button Sampler with 25-3 gel, 39% for BioSampler, and 13% for AerosolSense Sampler.