Abstract
INTRODUCTION: The dominant route of SARS-CoV-2 is by airborne transmission, through droplets and bioaerosols. Numerous studies have shown that healthcare workers are at risk when in contact with COVID-19 patients. However, there is a lack of information on the presence of SARS-CoV-2 from bioaerosols.
Detection of the virus in bioaerosols is vital to enable policymakers to design effective interventions to reduce risks of airborne transmission and ensure safety of workers. Therefore, this study aims to fill this gap by determining the best method for detection of SARS-C0V-2 in the air.
METHODS: This cross-sectional study was conducted from 23rd December 2021 to 8th February 2022 in two COVID-19 hospitals and one quarantine centre (QC) in Selangor state.
A low-volume air sampler (LVS), NIOSH BC-251, and a high-volume air sampler (HVS), Coriolis- µ, were placed at 1.0 and 2.5m from the COVID-19 patients. Airflow rates for LVS and HVS were at 3.5L/min for 4 hours and 150L/min for 10 min, respectively. Sampling was done in medical wards, intensive care units (ICU), emergency ward and halls in QC. The presence and concentration of SARS-CoV-2 in aerosols were determined using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and digital droplet PCR (ddPCR). We also used negative staining transmission electron microscopy (TEM) to visualize the virus's ultrastructure.
RESULTS: A total of 178 air samples were collected. All 33 control samples were negative, whilst 22 samples were detected positive by ddPCR with a detection rate of 15.2% and only 5 (3.4%) samples were detected by RT-PCR. Although detection by ddPCR was higher as compared to RT-PCR, there was no difference in detection rate by type of air sampler and distance. Detection rate of samples taken by LVS was 15.8% using ddPCR and 4% using RT-PCR, whilst detection rate of samples using HVS was 13.6% and 2.3% by ddPCR and RT-PCR, respectively. By distance, at 1m, detection rate using ddPCR was 18.2% and 6.1% using RT-PCR, whilst at 2.5m detection rate was 12.7% and 1.3% by ddPCR and RT-PCR, respectively. Significant differences were found across different healthcare facilities and locations. The highest positive detection rate was found in Hospital A (26.4%) followed by Hospital B (13.5%) and QC (2.5%). By location, the highest positive detection rate was found in the wards (25.8%) followed by ICU (15.4%). A total of 45 samples were taken on filters of LVS for imaging by TEM with a detection rate of 15.6%. Nail-like spikes or crowns can be seen and the diameter range of 60-100nm was in accordance with SARS-CoV-2.
DISCUSSION The presence of SARS-CoV-2 in the air at 2.5m from the patients indicates the potential for bioaerosol transmission. Use of ddPCR is recommended for detection of bioaerosol SARS-CoV-2 because of low concentrations in air. Use of LVS is better than HVS as detection by ddPCR was 1.2 and 1.4-fold higher in LVS compared to HVS and at distance of 1.0 and 2.5m, respectively. Findings of this study highlight the importance of airborne protective precautions among healthcare workers when providing care to COVID-19 patients.
Links
- https://apcph.cphm.my/wp-content/uploads/2022/07/APCPH2022-O-7.pdf
- https://apcph.cphm.my/events/oral-session-8-ballroom-B/
BibTeX (Download)
@proceedings{APCPH2022-O-7,
title = {Bioaerosol Sampling in Government Health Care Facilities Housing COVID-19 Patients in the Klang Valley: Comparison of Methods},
author = {Rosnawati Muhamad Robat and Rohaida Ismail and Nadia Mohamad and Kamesh Rajendran and Siti Aishah Rashid and Raheel Nazakat and Muhammad Alfatih Pahrol and Nik Muhammad Nizam Nik Hassan and Nurul Amalina Khairul Hasni and Fatin Amirah Suib and Nur Afrina Muhamad Hendri and A. S. Santhana Raj and Jeyanthi Suppiah and Ravindran Thayan and Rafiza Shaharudin},
url = {https://apcph.cphm.my/wp-content/uploads/2022/07/APCPH2022-O-7.pdf
https://apcph.cphm.my/events/oral-session-8-ballroom-B/},
year = {2022},
date = {2022-08-01},
urldate = {2022-08-02},
issue = {7},
abstract = {INTRODUCTION: The dominant route of SARS-CoV-2 is by airborne transmission, through droplets and bioaerosols. Numerous studies have shown that healthcare workers are at risk when in contact with COVID-19 patients. However, there is a lack of information on the presence of SARS-CoV-2 from bioaerosols.
Detection of the virus in bioaerosols is vital to enable policymakers to design effective interventions to reduce risks of airborne transmission and ensure safety of workers. Therefore, this study aims to fill this gap by determining the best method for detection of SARS-C0V-2 in the air.
METHODS: This cross-sectional study was conducted from 23rd December 2021 to 8th February 2022 in two COVID-19 hospitals and one quarantine centre (QC) in Selangor state.
A low-volume air sampler (LVS), NIOSH BC-251, and a high-volume air sampler (HVS), Coriolis- µ, were placed at 1.0 and 2.5m from the COVID-19 patients. Airflow rates for LVS and HVS were at 3.5L/min for 4 hours and 150L/min for 10 min, respectively. Sampling was done in medical wards, intensive care units (ICU), emergency ward and halls in QC. The presence and concentration of SARS-CoV-2 in aerosols were determined using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and digital droplet PCR (ddPCR). We also used negative staining transmission electron microscopy (TEM) to visualize the virus's ultrastructure.
RESULTS: A total of 178 air samples were collected. All 33 control samples were negative, whilst 22 samples were detected positive by ddPCR with a detection rate of 15.2% and only 5 (3.4%) samples were detected by RT-PCR. Although detection by ddPCR was higher as compared to RT-PCR, there was no difference in detection rate by type of air sampler and distance. Detection rate of samples taken by LVS was 15.8% using ddPCR and 4% using RT-PCR, whilst detection rate of samples using HVS was 13.6% and 2.3% by ddPCR and RT-PCR, respectively. By distance, at 1m, detection rate using ddPCR was 18.2% and 6.1% using RT-PCR, whilst at 2.5m detection rate was 12.7% and 1.3% by ddPCR and RT-PCR, respectively. Significant differences were found across different healthcare facilities and locations. The highest positive detection rate was found in Hospital A (26.4%) followed by Hospital B (13.5%) and QC (2.5%). By location, the highest positive detection rate was found in the wards (25.8%) followed by ICU (15.4%). A total of 45 samples were taken on filters of LVS for imaging by TEM with a detection rate of 15.6%. Nail-like spikes or crowns can be seen and the diameter range of 60-100nm was in accordance with SARS-CoV-2.
DISCUSSION The presence of SARS-CoV-2 in the air at 2.5m from the patients indicates the potential for bioaerosol transmission. Use of ddPCR is recommended for detection of bioaerosol SARS-CoV-2 because of low concentrations in air. Use of LVS is better than HVS as detection by ddPCR was 1.2 and 1.4-fold higher in LVS compared to HVS and at distance of 1.0 and 2.5m, respectively. Findings of this study highlight the importance of airborne protective precautions among healthcare workers when providing care to COVID-19 patients.},
howpublished = {published online at https://apcph.cphm.my},
note = {Type: ORAL PRESENTATION; Organisation: Institute for Medical Research},
keywords = {air sampler, bioaerosol, ddPCR, RT-PCR, SARS-CoV-2 RNA},
pubstate = {published},
tppubtype = {proceedings}
}