According to a first-of-its-kind study examining data from China’s busiest train, physical distancing is necessary to reduce the spread of COVID-19 on public transit. The study has revealed that there is a “high transmission risk” for COVID-19 among transit passengers. The high risk is on people sitting directly beside an infected person. The research was carried out by scholars from various Chinese institutions and the University of Southampton in the United Kingdom and was published on July 29 in Clinical Infectious Diseases.
They identified 2,334 “index patients” – passengers who began to indicate COVID-19 signs within 14 days of their journey and were diagnosed with COVID-19. Also, they identified 72,093 other passengers who sat within three rows and five seats of those index patients using data from Chinese health authorities and rail timetables. All the trips were taken on China’s G trains between mid-December and late February since the trains account for the majority of Chinese passenger rail trips and carry more passengers than all of the country’s airlines combined.
The study shows that 234 of the 72,093 commuters who sat close to an index patient ended up testing positive for the disease themselves. That is about 0.32 percent rate of attack. The rate of attack for travellers in the same row as the patient was 1.5 per cent. At the same time, those sitting in the seats next to the patient were 3.5 percent. The researchers revealed that it could be easier for the virus to spread without seats and headrests blocking its path. They also indicated that travellers have a higher probability of close contact with others in their row as they loiter around to accommodate bathroom breaks and departures. Also, families and friend groups have a habit of travelling together and are more likely to converse and intermingle which can facilitate virus transmission.
Middle or window seats did not seem to make a difference in the infection patterns, whether the index patient or the other passengers were sitting in aisle. As per trip duration, they found that the attack rate of 1.3 percent per hour for those passengers sitting right beside the patient and increased by 0.15 percent per hour of travel time. They also found that one person out 1,342 cases who took a seat that had just been vacated by an index patient later tested positive for COVID-19.
Although all of them were considered by health authorities to have most likely contracted it in that setting, the study does not prove that any of the 234 passengers who contracted COVID-19 after sitting close to an index patient definitively caught the virus while on the train. Furthermore, the research does not account for the possibility that people working on the train may have spread the infection or passengers who moved out of their assigned seats. However, the researchers say that their findings show the importance of distancing and taking other precautions when using public transit during the pandemic.