Monitoring for airborne respiratory viruses in a general pediatric ward in Singapore

Yadana, Su; Coleman, Kristen Kelli; Nguyen, Tham Thi; Hansen-Estruch, Christophe; Kalimuddin, Shirin; Thoon, Koh Cheng; Low, Jenny Guek Hong; Gray, Gregory Charles

Our pilot study provides molecular evidence of airborne respiratory viruses in a general pediatric ward in Singapore. Our results illustrate the potential of airborne respiratory viruses to circulate among hospitalized children, nursing staff and visitors. Additionally, we detected respirable virus-laden particles (≤4μm in diameter) which are thought to play a significant role in respiratory virus transmission. Aerosol samples testing positive for influenza A virus and adenovirus demonstrates the potential of these viruses to be transmitted via the airborne route. However, we were unable to document the viability of the virus particles and subsequent risk of infection. Additionally, the source of these viruses in the ward is unknown as we did not recruit human subjects nor have access to patient records. Despite previous successful attempts at using the NIOSH twostage sampler and PCR analyses to collect and detect aerosolized influenza A virus, 9, 10 all samples collected using the NIOSH sampler in this study tested negative for influenza A virus. We did capture and detect aerosolized adenovirus using the NIOSH samplers, however, none of the samples from the SKC filter cassettes tested positive for adenovirus. This result is inconsistent with our previous study which successfully recovered adenovirus DNA from aerosol samples collected using the SKC filter cassettes in patient waiting rooms. 11 Sampling sessions in our current study collected 840 L of air using one SKC filter cassette compared to the collection of 900 L of air per each of two SKC filter cassettes in our previous study. Additionally, SKC filter cassettes were mobilized in our current study and stationary in our previous study. The higher sample volumes collected in our previous study as well as the difference in mobility and location of the samplers might explain the difference in positive sample collections among studies.