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SARS-CoV-2 RNA Contaminated HVAC Filters and Indoor Surfaces in the Built Environment during Both Isolation and Quarantine Stages
JIN PAN, Seth Hawks, Aaron Prussin II, Nisha Duggal, Linsey Marr, Virginia Tech
Abstract Number: 632
Working Group: Infectious Aerosols in the Age of COVID-19
Abstract
There are relatively little data about the presence of SARS-CoV-2 in the built environment, except for hospitals, which accommodate only the sickest patients. To investigate the level of contamination on different surfaces, we collected heating, ventilation, and air conditioning (HVAC) filters and surface swab samples from university dormitory rooms housing students who were exposed and tested positive for COVID-19. Because patients shed more viruses earlier in the course of infection, we hypothesized that we would find more viruses in the quarantine dormitory, which housed students who had been exposed and were waiting for their test results, than in the isolation dormitory, which housed students who had already tested positive. We detected viral RNA from 9/21 (42.9%) filters, 49/125 (39.2%) surface samples, and 4/6 (66.7%) exhaust grilles in the public bathrooms of the two dormitories combined. We found no significant differences (p>0.05) in the positivity rate between quarantine and isolation rooms except for the floor swabs (p<0.05), which may be attributed to the difference between the hard vinyl floor in the quarantine rooms vs. the carpeted floor in the isolation rooms. Viral RNA was present in all five surface sample types, including the sink handle, sink floor, sink countertop, door handle, and thermostat panel, among which the sink floor exhibited the highest positive rate (14/28), followed by the thermostat panel (12/28). Viral RNA levels on surfaces varied widely, from 10 to 104 genome copies per swabbed area of ~10×10 cm2. We also tested the infectivity of samples with a Ct value lower than 33, and none of them were positive. Positive samples from the HVAC filters and bathroom exhaust grilles indicate that the virus was in the air, either directly from exhaled respiratory aerosols or resuspension of dust.