BACKGROUND AND PURPOSE:

• Birgand et al. (JAMA Network Open, 2020) reviewed current evidence on SARS-CoV-2 air contamination in different hospital areas

METHODS:

• Review and meta-analysis
• Data sources
  • MEDLINE | Embase | Web of Science databases (between January 1 and October 27, 2020)
• Inclusion criteria
  • Articles detailing SARS-CoV-2 air contamination in hospital settings
• Study design
  • Positivity rate of SARS-CoV-2 viral RNA and culture were calculated based on setting, clinical context, air ventilation system, and distance from patients
  • SARS-CoV-2 RNA concentrations in copies per meter cubed of air were pooled distribution analyzed by hospital areas
  • Particle sizes and SARS-CoV-2 RNA concentrations in copies or median tissue culture infectious dose (TCID50) per meter cubed were analyzed with categorization (aerosol particles <5 μm in diameter) 
    • <1 μm
    • From 1 to 4 μm
    • >4 μm

RESULTS:

• 24 cross-sectional observational studies | 471 air samples
• Air samples from close patient environments: 17.4% positive for SARS-CoV-2 RNA
• There was a significantly higher positive rate in ICU settings (P < 0.001)
  • ICU air samples: 25.2% positive
  • Non-ICU air samples: 10.7% positive
• There was no difference in air sample positivity rate according to the distance from patients (P = 0.22)
  • ≤1 m: 2.5% positive
  • >1 to 5 m: 5.5% positive
• Air sample positivity rate based on hospital area
  • Toilets: 23.8% positive
  • Clinical areas: 12.3% positive
  • Public areas: 33.3% positive
• Viral cultures performed: 5 studies | 81 total viral cultures
  • 8.6% of air samples from only 2 studies were positive | All from close patient environments (non-ICU rooms)
• Median (IQR) SARS-CoV-2 RNA concentrations varied based on location
  • Clinical areas: 1.0 × 10³ copies/m³ (0.4 × 10³ to 3.1 × 10³ copies/m³)
  • Toilets: 9.7 × 10³ copies/m³ (5.1 × 10³ to 14.3 × 10³ copies/m³)
• Protective equipment removal and patient rooms had high concentrations per titer of SARS-CoV-2
  • Concentration range: 0.9 × 10³ to 40 × 10³ copies/m³ 
  • Tissue culture range: 3.8 × 10³ to 7.2 × 10³ TCID50/m³
• Particle sizes peaks
  • Protective equipment removal and patient rooms: <1 μm
  • Staff offices: >4 μm

CONCLUSION:

• There was widespread contamination of hospital areas with SARS-CoV-2 RNA, but these air samples rarely contained infectious virus
• Severity of infections were not associated with increased air contamination
• There was a particularly high viral load in toilets and bathrooms, staff areas, and public hallways
• Authors note limitations, including lack of detail in studies used for the analysis
• The authors conclude

High viral loads found in toilets and/or bathrooms, staff areas, and public hallways argue for a careful consideration of these areas for the prevention of COVID-19 transmission

However, the presence of viable viruses should be primarily considered, given that it is a required link for the potential of cross-transmission 

Learn More – Primary Sources:

Assessment of Air Contamination by SARS-CoV-2 in Hospital Settings

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