Air recirculation role in the infection with COVID-19, lessons learned from Diamond Princess cruise ship

Abstract Objectives The Diamond Princess cruise ship is a unique case because it is the place at which testing capacity has reached its highest rate in the world during the COVID-19 pandemic. By analysing data that are collected about the current COVID-19 outbreak onboard, and by considering the design of the air conditioning system of the ship and virus transmission modes on cruise ships, this study aims to raise the hypothesis regarding the role of poor ventilation systems in the spread of COVID-19. Design This is an analysis of count data that has been collected by the onboard clinic up to the 20 th February 2020. Symptomatic infection rates during the quarantine period in cabins with previous confirmed cases are compared to these in cabins without previous confirmed cases. Results Symptomatic infection rate during the quarantine period in cabins with previously confirmed cases is not significantly higher than that in cabins without previously confirmed cases. Age doesn’t appear to be a cofounder. Conclusions Airborne transmission of COVID-19 through the ventilation system onboard could explain the virus spread into cabins during the quarantine period. Strength and Limitations of the study The study described an important intervention measure that is ignored by national authorities to reduce exposure and limit the transmission of COVID-19 in confined places. The study reviewed the Diamond Princess cruise ship deck plans, the design of its HVAC (heating ventilation air-conditioning) system, and previous viral outbreaks on cruise ships. The study considered all other studies that highlighted the airborne transmission mode of COVID-19. The study only considered the airborne transmission mode to explain the infection with COVID-19 in passengers’ cabins on the Diamond Princess cruise ship. The study used published count data to calculate the infection rates.