tetano
Editor, Senior Moderator
Proc Natl Acad Sci U S A
. 2021 Feb 23;118(8):e2015482118.
doi: 10.1073/pnas.2015482118.
Mechanistic transmission modeling of COVID-19 on the Diamond Princess cruise ship demonstrates the importance of aerosol transmission
Parham Azimi[SUP] 1 [/SUP], Zahra Keshavarz[SUP] 2 [/SUP], Jose Guillermo Cedeno Laurent[SUP] 2 [/SUP], Brent Stephens[SUP] 3 [/SUP], Joseph G Allen[SUP] 1 [/SUP]
Affiliations
Abstract
Several lines of existing evidence support the possibility of airborne transmission of coronavirus disease 2019 (COVID-19). However, quantitative information on the relative importance of transmission pathways of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains limited. To evaluate the relative importance of multiple transmission routes for SARS-CoV-2, we developed a modeling framework and leveraged detailed information available from the Diamond Princess cruise ship outbreak that occurred in early 2020. We modeled 21,600 scenarios to generate a matrix of solutions across a full range of assumptions for eight unknown or uncertain epidemic and mechanistic transmission factors. A total of 132 model iterations met acceptability criteria (R [SUP]2[/SUP] > 0.95 for modeled vs. reported cumulative daily cases and R [SUP]2[/SUP] > 0 for daily cases). Analyzing only these successful model iterations quantifies the likely contributions of each defined mode of transmission. Mean estimates of the contributions of short-range, long-range, and fomite transmission modes to infected cases across the entire simulation period were 35%, 35%, and 30%, respectively. Mean estimates of the contributions of larger respiratory droplets and smaller respiratory aerosols were 41% and 59%, respectively. Our results demonstrate that aerosol inhalation was likely the dominant contributor to COVID-19 transmission among the passengers, even considering a conservative assumption of high ventilation rates and no air recirculation conditions for the cruise ship. Moreover, close-range and long-range transmission likely contributed similarly to disease progression aboard the ship, with fomite transmission playing a smaller role. The passenger quarantine also affected the importance of each mode, demonstrating the impacts of the interventions.
Keywords: COVID-19; Diamond Princess Cruise Ship; aerosol transmission; built environment; transmission risk model.
. 2021 Feb 23;118(8):e2015482118.
doi: 10.1073/pnas.2015482118.
Mechanistic transmission modeling of COVID-19 on the Diamond Princess cruise ship demonstrates the importance of aerosol transmission
Parham Azimi[SUP] 1 [/SUP], Zahra Keshavarz[SUP] 2 [/SUP], Jose Guillermo Cedeno Laurent[SUP] 2 [/SUP], Brent Stephens[SUP] 3 [/SUP], Joseph G Allen[SUP] 1 [/SUP]
Affiliations
- PMID: 33536312
- DOI: 10.1073/pnas.2015482118
Abstract
Several lines of existing evidence support the possibility of airborne transmission of coronavirus disease 2019 (COVID-19). However, quantitative information on the relative importance of transmission pathways of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains limited. To evaluate the relative importance of multiple transmission routes for SARS-CoV-2, we developed a modeling framework and leveraged detailed information available from the Diamond Princess cruise ship outbreak that occurred in early 2020. We modeled 21,600 scenarios to generate a matrix of solutions across a full range of assumptions for eight unknown or uncertain epidemic and mechanistic transmission factors. A total of 132 model iterations met acceptability criteria (R [SUP]2[/SUP] > 0.95 for modeled vs. reported cumulative daily cases and R [SUP]2[/SUP] > 0 for daily cases). Analyzing only these successful model iterations quantifies the likely contributions of each defined mode of transmission. Mean estimates of the contributions of short-range, long-range, and fomite transmission modes to infected cases across the entire simulation period were 35%, 35%, and 30%, respectively. Mean estimates of the contributions of larger respiratory droplets and smaller respiratory aerosols were 41% and 59%, respectively. Our results demonstrate that aerosol inhalation was likely the dominant contributor to COVID-19 transmission among the passengers, even considering a conservative assumption of high ventilation rates and no air recirculation conditions for the cruise ship. Moreover, close-range and long-range transmission likely contributed similarly to disease progression aboard the ship, with fomite transmission playing a smaller role. The passenger quarantine also affected the importance of each mode, demonstrating the impacts of the interventions.
Keywords: COVID-19; Diamond Princess Cruise Ship; aerosol transmission; built environment; transmission risk model.