Probability and Estimated Risk of SARS-CoV-2 Transmission in the Air Travel System: A Systemic Review and Meta-Analysis

As an emerging virus, SARS-CoV-2 and the risk of transmission during air travel is of high interest. This paper estimates the probability of an infectious index passenger in the air travel system transmitting the SARS-CoV-2 virus to a fellow passenger during air travel. Literature was reviewed from May-September 2020 to identify COVID-19 cases related to the air travel system. The studies were limited to publicly available literature for passengers starting in January 2020; studies on other persons such as flight crews were not reviewed. A novel quantitative approach was developed to estimate air travel transmission risk that considers secondary cases, the overall air travel passenger population, and two correction factors for asymptomatic transmission and underreporting. There were at least 2866 index infectious passengers documented to have passed through the air travel system in a 1.4 billion passenger population. With correction factors, the global risk of transmission during air travel is 1:1.7 million. Uncertainty in the correction factors and a 95% credible interval indicate risk ranges from 1 case for every 712,000 travelers to 1 case for every 8 million travelers. The risk of COVID-19 transmission on an aircraft is low, even with infectious persons onboard.