RESEARCH & DEVELOPMENTEVALUATION OF SARS-CoV-2 AIR CONTAMINATIONIN HOSPITALS WITH CORIOLIS μ AIR SAMPLER
Department of Infectious Disease, Imperial College London, London, UK, W2 1PG.

/ CONTEXT
The current pandemic of Covid-19 has shown the vulnerability of our healthcare systems when faced with viral infections without aknown treatment. Understanding the transmission behavior of SARS-CoV-2 in the air will be a crucial step to managing the current
outbreak and design the appropriate prevention and control measures. In this document, we present how researchers in Imperial
College have been evaluating SARS-CoV-2 surface and air contamination in a hospital during the peak of the COVID-19 pandemic inLondon, using surface swabs and the Coriolis μ air sampler coupled with RT-qPCR and viral culture.

/ PROTOCOL/ RESULTS

Sampling design: Surface and air samples were collected in 8
different sites including 7 clinical areas and 1 public area at a
North Western London hospital, during the peak of the Covid19 pandemic (from April 2nd to April 20th, 2020). The list of sites
can be found in Figure 1. All inpatient wards were fully
occupied by patients with Covid-19 at the time of sampling,
apart from the Emergency Department .
In each of these clinical areas, 4 air samples were collected (5 airsamples were collected in the Emergency Department, and 3 inpublic areas of the hospital). Surface samples were collected byswabbing approximately 25 cm2 of items in the immediate
vicinity of each air sample.
Collection: Sampling was carried out with the Coriolis μ air
sampler (Bertin Technologies, France) at 100L/min for 10 min(corresponding to 1m3 of air), with 5 mL DMEM.
RT-qPCR Analysis: The RNA extraction step was realized on
140μL of sample using Qiagen viral RNA mini kit.
This was followed by absolute quantitative Real-time PCRtargeting the envelop (E) gene of SARS-CoV-2 with AgPath
One-step RT-PCR (Life Technologies).

/ CUSTOMER[1] Zhou, J. (2020). Investigating SARS-CoV-2
surface and air contamination in an acutehealthcare setting during the peak of the Covid-19
pandemic in London. Medrxiv.

Operating theatres

Operating theatres

Figure 1: PCR results from air samples. Samples where both of the PCRs
performed from an air or surface sample detected SARS-CoV-2 RNA weredefined as positive, and samples where one of the two PCRs performed froman air or surface sample detected SARS-CoV-2 RNA were defined as suspected.
Adapted from [1].

/ CONCLUSION
SARS-CoV-2 RNA was detected on 114/218 (52.3%) of the surface samples and 14/31 (38.7%) of the air samples collected withthe Coriolis μ air sampler. The concentrations detected indicated a viral load that would not be culturable, which was confirmedby viral culture assays. Viral RNA was detected on surfaces and in the air in public areas of the hospital but was more likely to befound in areas immediately. These results show that the Coriolis μ air sampler can be used successfully to evaluate SARS-CoV-2
air contamination, and also set guidelines for the use of PPE, social distancing, and hygiene in acute healthcare settings.

CONTACT
Email: air-sampler@bertin-instruments.com
www.bertin-instruments.com

CNIM group

CORM-026-039-B

Viral culture: Vero E6 (African Green monkey kidney) andCaco2 (human colon carcinoma) cells were used to culture virus
from air and environmental samples.