Reusable Clip-On Device Assesses Exposure to SARS-CoV-2
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Scientists from Yale University have developed a wearable air sampler that has been tested for its ability to detect airborne SARS-CoV-2. The study results are published in Environmental Science and Technology Letters.1
Detecting airborne SARS-CoV-2
As we continue to live through the COVID-19 pandemic, we learn more about the SARS-CoV-2 virus, how it impacts the human body, is transmitted from person to person and the most effective ways to prevent and treat it. As this knowledge grows, it informs our ability to develop new ways to reliably test for exposure to or infection with the virus across different settings.
What do we mean by airborne transmission of SARS-CoV-2? When individuals that are infected with SARS-CoV-2 exhale, they release viral particles in aerosol or droplet form. “This can be from coughing or sneezing, but also when they speak or breathe,” explains Dr. Krystal Pollitt, assistant professor of epidemiology at the Yale Institute for Global Health. “While the larger droplets can settle to the ground quickly (seconds to minutes), smaller aerosols can remain in the air for longer periods of time (minutes to hours).” The virus can therefore be transmitted from one individual to another via inhalation of the aerosol or droplets that contain the virus.
Devices capable of detecting airborne SARS-CoV-2 could help to inform individuals when they have unknowingly been exposed to the virus. While several of these devices have already been developed and tested – in airport settings, for example – they are typically large and limited in terms of mobility, resembling the bulky printers you might encounter in an office.
A compact device for detecting exposure to respiratory viruses
Pollitt and colleagues have been working on a more compact air sampling device that is wearable, known as “The Fresh Air Clip”. Initially, it was designed to test a person’s exposure to airborne chemical contaminants and is used by people living in the UK and 13 other countries across the world.2,3,4 “Chemicals are taken up by the polymer film in the wearable device and we use mass spectrometry to detect exposures […] We typically detect ~500 different chemicals using this tool,” says Pollitt.
When the COVID-19 pandemic began, the researchers pivoted their intended use of the clip for detecting chemical exposure to respiratory virus exposure.
“The Fresh Air Clip serves to identify exposure events early, allowing for rapid action to be taken to get tested or quarantine, preventing viral spread should the participant not have had this early detection of exposure,” Pollitt says.
Design and testing of The Fresh Air Clip
The device is made from a polydimethylsiloxane (PDMS) surface that adsorbs aerosols and droplets potentially containing the virus. This film lies within a chamber where the clip, which has a magnetic fastener, is contained. The polymer film is used as a sampler for a subsequent polymerase chain reaction (PCR) test that can be used to estimate airborne concentrations of SARS-CoV-2.
The research team first tested The Fresh Air Clip at Yale New Haven Hospital. “We placed the clips in COVID-19 patient rooms and found that we were able to detect SARS-CoV-2,” says Pollitt. “We then did some controlled testing in the lab to measure how quickly airborne virus was collected by the polymer film in the clip.” To ensure the research team’s safety, a bacteriophage – which has similar properties to SARS-CoV-2 – was utilized for the laboratory testing.
Next, the clip was distributed to 62 study participants across Connecticut, who were asked to wear the device for 5 days. “The number of virus copies collected on each clip worn by study participants was measured using PCR,” says Pollitt. SARS-CoV-2 was detected by PCR in five of the clips; four of which had been worn by restaurant servers, and one that was worn by a member of staff at a homeless shelter.
“Our findings demonstrate that PDMS-based passive samplers may serve as a useful exposure assessment tool for airborne viral exposure in real world high-risk settings and provide avenues for early detection of potential cases and guidance on site-specific infection control protocols that pre-empt community transmission,” the authors write in the paper.
Pollitt says that the research team would have liked to report on the use of the clip in a larger population in a wider range of environments. Since the initial study was completed, they have continued to utilize the clip in different indoor settings to assess transmission risk – this data is not yet published.
The Fresh Air Clip is reusable
Benefits of The Fresh Air Clip include the fact that it is both lightweight and inexpensive. But is it environmentally “friendly”? Major concerns surrounding the pandemic’s toll on the Earth’s environment have been expressed, what with the requirement for face masks, gloves and other protective equipment to prevent infection. “The Fresh Air Clips are reusable – this was an important consideration in the design process,” Pollitt describes. “We prepare a polymer film that is contained in the clip to collect the virus. This polymer is replaced with a new film so the device can be reused.”
The device has not yet been commercialized. At this stage, the scientists are keen to expand its use, and are “exploring how best to scale application in workplaces, schools and with community members,” Pollitt concludes.
Dr. Krystal Pollitt was speaking to Molly Campbell, Senior Science Writer for Technology Networks.
References:
1. Angel DM, Gao D, DeLay K, et al. Development and application of a polydimethylsiloxane-based passive air sampler to assess personal exposure to SARS-CoV-2. Environ Sci Technol Lett. 2022. doi: 10.1021/acs.estlett.1c00877.
2. Lin EZ, Esenther S, Mascelloni M, Irfan F, Godri Pollitt KJ. The fresh air wristband: A wearable air pollutant sampler. Environ Sci Technol Lett. 2020;7(5):308-314. doi: 10.1021/acs.estlett.9b00800.
3. Guo P, Lin EZ, Koelmel JP, et al. Exploring personal chemical exposures in China with wearable air pollutant monitors: A repeated-measure study in healthy older adults in Jinan, China. Environ Int. 2021;156:106709. doi: 10.1016/j.envint.2021.106709.
4. Koelmel JP, Lin EZ, DeLay K, et al. Assessing the external exposome of South African children using wearable passive samplers and highresolution mass spectrometry. Published as a pre-print. Research Square. 2021. doi: 10.21203/rs.3.rs-828351/v1.
