Ocular Microbiology and Immunology Group
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2020 OMIG Abstract

SAVES: Recovery of SARS-CoV-2 from Aerosol Spread

Miel Sundararajan, MD^1,2, Thuy A. Doan, MD, PhD^1,2, Gerami D. Seitzman, MD^1,2,
Julie M. Schallhorn, MD, MS^2
1Francis. I Proctor Foundation; University of California, San Francisco, San Francisco, CA;
²Department of Ophthalmology, University of California, San Francisco, San Francisco, CA

Purpose: Determining the modes of transmission of SARS-Cov2 is of particular interest in ophthalmology because of the close proximity of physicians’ faces to patients’ during ophthalmic examinations and procedures. The potential for aerosolization of SARS-CoV-2 remains inconclusive and poses a major health risk to both the public and medical professionals. Potential for transmission over short, approximating slit lamp, distances is unknown. Personal protective equipment (PPE) recommendations vary based on need for aerosol versus droplet protection. The study aims to evaluate the potential for SARS-CoV-2 aerosolization during speech at a range that may be meaningful to ophthalmologists. Specifically, it examines the shedding of detectible viral particles at close range during speech and/or normal respiration, as this would inform guidance on appropriate PPE for ophthalmic patient interaction.

Methods:: This is a prospective cross-sectional study. Symptomatic patients undergoing COVID-19 screening at a single UCSF drive-through respiratory testing facility were consented in advance by telephone. In additional to routine nasopharyngeal PCR testing, study protocol was performed: patients held a standardized piece of filter paper 4-5 inches from the face and vocalized for one minute. RT-PCR was performed on nasopharyngeal and filter paper samples.

Results: 439 patient samples were processed. Of these, 5 were positive for SARS-CoV-2 RNA by RT-PCR on standard nasopharyngeal samples (1.14%), while 434 were negative. None of the 439 aerosolized samples collected on filter paper were positive for SARS-CoV-2 RNA by RT-PCR. Specifically, 0 of 5 nasopharyngeal swab positive patients demonstrated RT-PCR positivity on filter paper samples (95% CI 0 to 0.522). Furthermore, 0 of 434 nasopharyngeal swab negative patients were positive for SARS-CoV-2 RNA on filter paper samples (95% CI 0 to 0.008).

Conclusion: In the current climate, the local infection rate among symptomatic patients is low. Only a small percentage of enrolled patients were found to be positive for SARS-CoV-2 RNA on RT-PCR of nasopharyngeal sample, proving the major limitation to this study. However, it is reassuring that none of these patients shed viral particles at close range through prolonged speaking and breathing. Universal masking and additional hygiene practices likely reduce the risk of COVID-19 infection further.

Disclosure: S (TA Doan)

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