Comparing and validating air sampling methods for SARS-CoV-2 detection in HVAC ducts of student dorms

Area of Science:

• Environmental microbiology
• Public health
• Molecular diagnostics

Background:

• Airborne pathogenic respiratory viruses, like SARS-CoV-2, pose significant public health threats.
• Early detection in shared environments, such as dormitories, is crucial for implementing timely control measures.
• Heating, Ventilation, and Air Conditioning (HVAC) systems can potentially circulate and be monitored for airborne pathogens.

Purpose of the Study:

• To extend and validate the detection of SARS-CoV-2 in dormitory HVAC systems.
• To compare the efficacy of different air sampling methods and media for virus detection.
• To correlate HVAC air sampling results with individual testing data.

Main Methods:

• Air samples were collected from dormitory HVAC systems using Filter Cassettes, BioSampler, AerosolSense Sampler, and Button Sampler with various media.
• Quantitative Reverse-Transcription PCR (qRT-PCR) was optimized for SARS-CoV-2 detection in air samples.
• Sampling results were compared with individual student saliva and nasopharyngeal PCR tests.

Main Results:

• SARS-CoV-2 was detected in HVAC air samples from both unknown (73% detection rate) and known (78% detection rate) COVID-19 environments.
• All tested sampling methods detected the virus, with AerosolSense (63%) and BioSampler (61%) showing higher detection rates.
• Detection rates were significantly higher compared to Filter Cassettes (25%) and Button Sampler (23%).

Conclusions:

• Pathogenic respiratory viruses, including SARS-CoV-2, are detectable in large building HVAC systems using optimized sampling and qRT-PCR methods.
• HVAC air sampling can serve as a valuable component of an early warning system for airborne virus circulation.
• While multiple methods are effective, AerosolSense and BioSampler demonstrated superior performance in this study, though further research is needed to determine the most sensitive method.