Rapid monitoring of indoor airborne influenza and coronavirus with high air flowrate electrostatic sampling and PCR analysis

The World Health Organization has raised concerns about the possibility of airborne transmission in enclosed and poorly ventilated areas. Therefore, rapid monitoring of airborne viruses is necessary in multi-use facilities with dense population. Accordingly, an electrostatic air sampler (250 L/min) was developed in this work to obtain indoor viral aerosol samples for analysis via the Polymerase Chain Reaction (PCR). Aerosol tests with H1N1 and HCoV-229E were performed to evaluate the sample collection efficiency. PCR analysis, along with another aerosol test, was conducted to evaluate the recovery of the virus particles collected by the sampler. In laboratory tests, our electrostatic sampler obtained viral samples that were detectable by PCR under the simulated viral pandemic scenario (3000 RNA copies per cubic meter of air) within 40 min. The resulting cycle threshold (C_t) values were 35.07 and 37.1 for H1N1 and HCoV-229E, respectively. After the performance evaluation in the laboratory, field tests were conducted in a university classroom from October 28 to December 2, 2022. Influenza A and HCoV-229E were detected in two air samples, and the corresponding C_t values were 35.3 and 36.8. These PCR results are similar to those obtained from laboratory tests, considering the simulated viral pandemic scenario.