Detection of influenza virus in air samples of patient rooms

Abstract

Background Understanding the transmission and dispersal of influenza and respiratory syncytial virus (RSV) via aerosols is essential for the development of preventative measures in hospital environments and healthcare facilities. Methods During the 2017-2018 influenza season, patients with confirmed influenza or RSV infections were enrolled. Room air samples were collected close to (0.30 m) and far (2.20 m) from the patient’s head. Real-time polymerase chain reaction (PCR) was used to detect and quantify viral particles in the air samples. Plaque assay was used to determine the infectiousness of the detected viruses. Findings Fifty-one air samples were collected from the rooms of 29 patients with laboratory-confirmed influenza; 51% of the samples tested positive for influenza A virus (IAV). Among IAV-positive patients, 65% were emitters (have at least one positive air sample) reflecting a higher risk of nosocomial transmission compared to non-emitters. The majority (61.5%) of the IAV-positive air samples were collected at 0.3 m distance from the patients’ head, while the remaining were collected at 2.2 m. The positivity rate of IAV in air samplers was influenced by the distance from the patient’s head and the day of collection post-hospital admission. Only three patients with RSV infection were recruited and none were emitters. Conclusion This study demonstrates that influenza can be aerosolized beyond one meter in patient rooms, a distance considered to be safe by infection control practices. Further investigations are needed to determine the extent of infectivity of the aerosolized virus particles.

Small quantities of respiratory syncytial virus RNA only in large droplets around infants hospitalized with acute respiratory infections

“…In the 1980s it was demonstrated that healthy individuals only became infected upon self-inoculation after touching contaminated surfaces, or through close contact with infected infants, but not by solely sitting in the same room at a distance of > 1.8 m away from the patient’s bed [ 11 ]. These observations were later supported by several air sampling studies, in which RSV was detected infrequently, or not at all, in the air around infected patients [ 12 – 15 ]. In contrast to these studies, Aintablian and colleagues were able to collect RSV RNA from the air around RSV infected patients between 0.3 and 7 m away from the patient’s head, with a higher likelihood of RSV detection close to the patient [ 16 ].…”

“…Moreover, in a recent study by Chamseddine et al, none of the collected air samples around RSV infected patients were positive for RSV RNA, while half of the air samples collected around influenza A virus-infected patients were positive for influenza virus RNA. However, attempts to isolate infectious influenza virus from these samples were not successful [ 15 ].…”

Small Quantities of Respiratory Syncytial Virus RNA Only in Large Droplets Around Infants Hospitalized With Acute Respiratory Infections

“…Moreover, in a recent study by Chamseddine et al, none of the collected air samples around RSV infected patients were positive for RSV RNA, while half of the air samples collected around in uenza A virus infected patients were positive for in uenza virus RNA. However, attempts to isolate infectious in uenza virus from these samples were not successful(15).Contrasting results were previously reported byKulkarni et al, where air sampling around infants with RSV-con rmed bronchiolitis in general wards of a pediatric hospital resulted in the collection of high amounts of infectious RSV from the air…”

“…Moreover, in a recent study by Chamseddine et al, none of the collected air samples around RSV infected patients were positive for RSV RNA, while half of the air samples collected around in uenza A virus infected patients were positive for in uenza virus RNA. However, attempts to isolate infectious in uenza virus from these samples were not successful (15).…”

“…In the 1980s it was demonstrated that healthy individuals only became infected upon selfinoculation after touching contaminated surfaces, or through close contact with infected infants, but not by solely sitting in the same room at a distance of > 1.8 m away from the patient's bed (11). These observations were later supported by several air sampling studies, in which RSV was detected infrequently, or not at all, in air around infected patients (12)(13)(14)(15). In contrast to these studies, Aintablian and colleagues were able to collect RSV RNA from the air around RSV infected patients between 0.3 and 7 m away from the patient's head, with a higher likelihood of RSV detection close to the patient (16).…”