Coronavirus study finds train travel safer than first thought

Study explored the risks to travellers who sat in seats formerly occupied by infected passengers

Trains are seen as Covid hotspots but the WorldPop study belies this assumption. AFP

The chances of passengers catching Covid-19 on a train are not as high as people seem to think, according to a new study by British and Chinese scientists.

Researchers stopped short of completely debunking widely held beliefs, however, saying that rail travellers are still at increased risk of infection.

How the study was carried out

The study was drawn from high-speed routes in China in the first three months of 2020, when the virus was spreading rapidly.

Using sophisticated modelling it analysed the interactions of the 2,000+ "index patients" (Covid-infected people) who had used the network during this period.

The modellers explored the risks to travellers who sat in seats or rows formerly occupied by index patients.

The metric used to assess risk was called the "attack rate": the number of passengers in a given seat diagnosed with Covid-19, divided by the total number of passengers travelling in the same seat.

The results

Passengers travelling in seats directly adjacent to an index patient suffered the highest level of transmission with an average of 3.5 per cent contracting the disease. For those sitting on the same row, the figure was 1.5 per cent.

Somewhat counter-intuitively, researchers found that only 0.075 per cent of people who used a seat previously occupied by an index patient went on to contract the disease.

The below graphic, produced by modellers at the University of Southampton, shows the attack rate of Covid-19 per different seats and co-travel time on one of the trains studied.

What the researchers said

Study lead Dr Shengjje Lai said the findings pointed to the importance of reducing passenger density on trains and promoting good personal hygiene measures, such as the use of face masks. He also suggested that compulsory temperature checks before boarding might be a helpful measure.

Professor Andy Tatem, director of research firm WorldPop, added: "[The study] shows that the transmission risk not only relates to the distance from an infected person but also the time in their presence.

"We hope it can help to inform authorities globally about measures needed to guard against the virus and, in turn, help to reduce its spread."