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Detection of SARS-CoV-2 in aerosol and surface samples in high acuity hospital settings during community epidemic
C Raina MacIntyre1, Adriana Notaras1, Noor Bari1
1The Biosecurity Program, Kirby Institute, University of New South Wales, Sydney, NSW, Australia.
Rationale:
Nosocomial transmission of SARS-CoV-2 is multifactorial and may vary between clinical sites.
Objectives:
To measure SARS-CoV-2 in the air and on surfaces within the Intensive Care Unit (ICU) and Emergency Department (ED).
Methods:
We conducted an air and surface-sampling study of SARS-CoV-2 in the ED and ICU of a hospital in Sydney.
Measurements:
We sampled air, patient equipment, and personal protective equipment during two community COVID-19 epidemics. SARS-CoV-2 was detected using quantitative reverse transcription polymerase chain reaction (RT-qPCR). Carbon dioxide (CO2) was measured simultaneously, with <800 ppm indicating good air quality.
Main Results:
SARS-CoV-2 genetic material was detected in 39% of 51 aerosol samples, with mean CO2 levels consistently <800 ppm for positive samples. The ED had more detections than the ICU (80% vs. 20%; p < 0.0027) and a higher mean CO2 level than the ICU (669 ppm vs. 522 ppm; p < 0.05). The ED waiting room, acute ward, and ICU staff tearoom showed higher detection rates than the ICU ward area. SARS-CoV-2 was detected in air samples in the ED a week before an outbreak was declared, and both inside and outside a COVID-19 patient's negative-pressure ICU room, where high-flow nasal prongs and a glove tested positive.
Conclusion:
During community epidemics, SARS-CoV-2 genetic material is detected in hospital air despite good ventilation. Enhanced protection with masks, vaccines, and portable air purifiers, especially in high-risk areas, may mitigate nosocomial transmission, including among staff. Air sampling can provide an early warning of an outbreak and help identify areas that need enhanced infection control.
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