Role of fomites in SARS transmission during the largest hospital outbreak in Hong Kong

Abstract

The epidemic of severe acute respiratory syndrome (SARS) had a significant effect on global society in the early 2000s and the potential of its resurgence exists. Studies on the modes of transmission of SARS are limited though a number of outbreak studies have revealed the possible airborne route. To develop more specific and effective control strategies, we conducted a detailed mechanism-based investigation that explored the role of fomite transmission in the well-known Ward 8A outbreak. We considered three hypothetical transmission routes, i.e., the long-range airborne, fomite and combined routes, in 1,744 scenarios with combinations of some important parameters. A multi-agent model was used to predict the infection risk distributions of the three hypothetical routes. Model selection was carried out for different scenarios to compare the distributions of infection risk with that of the reported attack rates and select the hypotheses with the best fitness. Our results reveal that under the assumed conditions, the SARS coronavirus was most possible to have spread via the combined long-range airborne and fomite routes, and that the fomite route played a non-negligible role in the transmission.

Evaluating the commercial airliner cabin environment with different air distribution systems

“…Dose-response models are more biologically plausible, since they are based on experimental infectious dose data. 57 However, apart from indirect studies 58 Supply air distribution was assumed to be uniform, and a standard manikin was used to represent passengers. The airflow boundary conditions would be very complex in a real, operating airplane cabin, 59 and passengers could have different body sizes, poses, and metabolic rates.…”

What we know so far: COVID-19 current clinical knowledge and research

“…19 Fomite spread via contaminated surfaces is also probable, based on SARS-CoV. [25][26][27] Nosocomial spread is also a significant concern. 28 The mean incubation period is brief, reported as 5.2 days, with the 95th percentile of the distribution at 12.5 days (95% confidence interval 9.2-18).…”

Severe Acute Respiratory Syndrome

“…48 A multiagent modeling analysis of 1744 scenarios was used to examine the contribution by different modes of transmission in the ward 8A outbreak and found that SARS-CoV most likely had spread via the combined long-range airborne and fomite routes, while fomites played a nonnegligible role in the transmission. 49 In Toronto, SARS-CoV was found on polymerase chain reaction (PCR) testing of environmental air samples taken from a hospital room occupied by a patient with SARS-CoV infection, as well as from conventional surface swabs taken from a bed table, a patient's television remote control, and a medication refrigerator door at a nurses' station. 50 The possibility of airborne transmission as indicated by the data emphasizes that it is imperative to take appropriate respiratory protection in addition to strict surface hygiene practices.…”