Three studies published late last week describe in-flight COVID-19 transmission, with one involving a single symptomatic passenger who likely infected at least 12 others during an international flight.Seat proximity and increased riskThe first study, published in Emerging Infectious Diseases, involved an epidemiologic investigation of all traceable passengers and crew members on a 10-hour Vietnam Airlines flight 54 (VN54) from London to Hanoi, Vietnam, on Mar 1 that resulted in 15 ill people in addition to the index patient.Researchers interviewed, tested, and quarantined the passengers and crew and traced their close contacts to estimate the likelihood of transmission of SARS-CoV-2, the virus that causes COVID-19, on the flight and