Title: SARS-CoV-2 Aerosols in Homes of COVID-19 Infected Adults: Presence and Control

Abstract:

Introduction. One key challenge is to reduce secondary attack rates among household contacts, which are estimated by the CDC to be as high as 50%. In addition to close interpersonal contact, emerging evidence suggests that airborne transmission is important for spreading SARS-CoV-2 infections in enclosed and/or poorly ventilated spaces, such as homes. Since one of the virus transmission routes is airborne, we hypothesized that its spread could be controlled using portable air cleaners (PACs). However, the existing data are sparse and based on scripted scenarios. Here, we report the first naturalistic intervention study to reduce SARS-CoV-2 airborne transmission using PACs with HEPA filters in the homes of COVID-19-infected individuals.

Methods. Subjects were recruited in the fall/winter of 2020-2021 through an email flyer delivered at the time of notification of test positivity. Saliva screening at the time of the first visit verified continued positivity for all reported subjects. 24-hr air samples of total aerosols were collected in the isolation room (the primary room used by the subject) and the common room (a secondary room) on PTFE filters using open-face filter holders (CH Technologies, Westwood, NJ, USA and SKC, Inc. Eighty-Four, PA, USA) or modified IMPACT filter samplers (SKC Inc.) and Leland Legacy pumps (SKC Inc.) operated at 10 L/min. The PAC was placed only in the primary room, away from any walls. In one 24-hr period, the PAC was operated with a HEPA filter and, during the other, without a filter ("sham" period). The filtration and treatment order was randomized. Samples were analyzed by RT-PCR for expression of three distinct SARS-CoV-2 genes: N, ORF1ab, and S. Samples were considered positive if any one gene and internal control (MS2 phage) were detected at Ct ≤ 40.

Results and Conclusions. Samples were collected in the homes of 17 individuals with newly diagnosed COVID-19 infection. Seven out of sixteen (44%) air samples in primary rooms were positive for at least one gene during the sham period. Seven out of fifteen (47%) air samples in secondary rooms were also positive during the sham period. The data also suggested a strong association between the amount of viral RNA in an infected person's saliva and the likelihood of airborne virus being detected in the primary room. During the filtration period, the proportion of positive aerosol samples decreased to four out of sixteen residences (25%) (p=0.223).

Conclusions

Thus, our results show that SARS-CoV-2 RNA is common in the home air of COVID-19 patients. Therefore, using air cleaners to reduce SARS-CoV-2 exposure should be considered part of guidance for caring for COVID-19 patients in residential and community-based indoor environments, especially in situations of limited space and resources.

Acknowledgments

Supplement to NIEHS P30 Center ES05022, NIH/CATS (UL1TR003017), NIEHS Training Grant in Exposure Science (1T32ES019854; Dr. Nirmala T. Myers), and NIOSH ERC (T42OH008422; Dr. Frederic T. Lu).

Recent Publications

1. Laumbach, R., Mainelis, G., Black, K., Myers, N.T., Ohman-Strickland, P., Alimokhtari, S., Hastings, S., Resende, A.D., Legard, A., Calderón, L., Lu, F., and Kipen, H. (2021) Presence of SARS-CoV-2 in residences of adults with COVID-19, Annals of the American Thoracic Society, 19(2): 338. Link.
2. Myers, N.T., Laumbach, R., Black, K., Ohman-Strickland, P., Alimokhtari, S., Legard, A., Resende, A.D., Calderón, L., Lu, F., Mainelis, G.*, and Kipen, H. (2022) Portable Air Cleaners and Residential Exposure to SARS-CoV-2 Aerosols: A Real-World Study, Indoor Air, 32(4). Link.
3. Grogan, S. and Mainelis, G. (2022) Effect of Sampling Duration on Culturable and Viable Bioaerosol Determination when using Rutgers Electrostatic Passive Sampler (REPS), Journal of Aerosol Science, 106066. Link.
4. Myers, N. T., Han, T.T., Li, M.-L., Brewer, G.; Harper, M., Mainelis, G. (2021) Impact of Sampling and Storage Stress on the Recovery of Airborne SARS-CoV-2 Virus Surrogate Captured by Filtration, Journal of Occupational & Environmental Hygiene, 18 (9), 461-475. Link.
5. Metaxatos, A., Manibusan, S., and Mainelis, G. (2022) Investigation of sources, diversity, and variability of bacterial aerosols in Athens, Greece: a pilot study, Atmosphere, 13(1), 45. Link.

Biography:

Gediminas “Gedi” Mainelis is a Professor in the Department of Environmental Sciences at Rutgers, the State University of New Jersey, USA. He has a Bachelor’s degree in physics from Vilnius University, Lithuania, and a Ph.D. in Environmental Health from the University of Cincinnati, Ohio, USA. His research focuses on various aspects of bioaerosol science, including sampling and analysis methods, exposure assessment, and airborne microbiomes. Over the past years, his research expanded to investigate exposures to manufactured nanoparticles and explore indoor air issues. Several of his current projects focus on COVID-19 issues. His research efforts have resulted in more than 110 peer-reviewed publications, book chapters, and several patents. In addition, multiple papers from his group have been included in the most downloaded article lists of various peer-reviewed journals. Dr. Mainelis has served as Chair of the Bioaerosols and Health-Related Aerosol working groups of the American Association for Aerosol Research (AAAR). He is currently an editor (associate) of the Aerosol and Air Quality Research journal. Prof. Mainelis is a recipient of the Research Excellence Award from Rutgers University and the Lyman A. Ripperton Environmental Educator Award presented by the A&WMA.