Genomic Evidence of In-Flight Transmission of SARS-CoV-2 Despite Predeparture Testing

I n response to the growing international risks as- sociated with importation of coronavirus disease (COVID-19), on March 20, 2020, New Zealand closed its borders to all but New Zealand citizens, permanent residents, and persons with an exemption (1).On April 9, 2020, to better control importation risks, New Zealand implemented a system of managed isolation and quarantine (MIQ) at the border.Persons arriving in New Zealand were required to stay in a government-assigned MIQ facility for at least 14 days before entering the New Zealand community.In June 2020, a system of testing persons who were returning to New Zealand and staying in MIQ facilities was instituted; nasopharyngeal swabs were taken on approximately the third and the twelfth day of the quarantine period and from anyone in whom symptoms developed or those identified as close contacts of persons with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive test results.On September 29, 2020, flight EK448, which originated in Dubai, United Arab Emirates, with a stop in Kuala Lumpur, Malaysia, landed in Auckland, New Zealand.During the required 14-day MIQ period, 7 passengers who had traveled on the flight received positive SARS-CoV-2 test results.The 7 passengers had begun their journeys from 5 different countries before a layover in Dubai; predeparture SARS-CoV-2 test results were negative for 5 (Figure 1).These 7 passengers had been seated within 4 rows of each other during the ≈18-hour flight from Dubai to Auckland.Because recent studies have reported conflicting findings of the risks associated with in-flight transmission (2-4), we undertook a comprehensive investigation to determine the potential source of infection of these travelers.