Centralised Air Sampling from a Ventilation System for the Surveillance of Respiratory Pathogens

Background: The COVID-19 pandemic has triggered a renewed interest in indoor air sampling for infectious disease surveillance. However, scalability is currently limited, as samples are usually collected in a single indoor space. An alternative is to place the device within a heating, ventilation, and air conditioning system (HVAC), but this approach has not been tested against room air sampling.Methods: In this observational study, we sampled the air in an indoor fitness centre for 2 or 6 hours, simultaneously in three locations of the main exercise hall and in the return plenum of the HVAC system. Samples were collected twice weekly for 11 weeks. All samples were tested for 29 respiratory pathogens using PCR. We compared the ventilation system and exercise hall air with regards to presence and concentration of pathogens.Findings: Samples collected in two locations in the exercise hall had a similar overall sensitivity to the HVAC sampler for detecting pathogens, while a third sampling location was associated with significantly lower sensitivity. Overall, the pathogen concentration was similar in the ventilation system and the exercise hall air (ratio: 1·­0; 95% CI: 0·8 to 1·3).Interpretation: Our results show that air sampling within a ventilation system can have equal or even higher sensitivity for detecting respiratory pathogens, compared to room-based sampling. Thus, placing samplers within central ventilation systems could increase the scalability of air sampling for infectious disease surveillance.Trial Registration:Funding: KU Leuven, European Union (DURABLE project), Research Foundation Flanders.Declaration of Interest: Our lab has received a number of sampling cartridges free of charge from the manufacturer, Thermo Fisher Scientific.Ethical Approval: This observational study received approval from the Ethics Committee Research UZ/KU Leuven (study number S66518). The requirement for informed consent from individual attendees was waived, as no individual samples or personal data were collected. Sampling took place after the management of the fitness centre had agreed to take part in the study.