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If you’ve returned to work and you commute on a train, you’ll probably want to know more about the risks of catching Covid-19 if someone in your carriage is infected.
A new study from the University of Southampton shines a light on this. Based on high-speed train routes in China, researchers found that for train passengers sitting within three rows (widthwise) and five columns (lengthwise) of an infected person, between zero and 10% of passengers caught the disease.
There were two key factors that increased the likelihood of catching Covid-19: how long a person was travelling on the train and how close they were sat to the infected person. Lead investigator Dr Shengjie Lai said these “can make a big difference” as to whether Covid-19 is passed on.
The WorldPop team at the University of Southampton conducted their study by analysing data of train travel in China between 19 December 2019 and 6 March 2020. This included 2,334 infected people and 72,093 close contacts. Their travel times ranged from between less than an hour to eight hours.
Passengers travelling in seats either side of an infected person suffered the highest level of transmission. For those sitting on the same row, there was also an increased risk of catching Covid-19.
The risk of transmission increased slightly for every hour a person travelled on the same carriage as an infected person.
Interestingly, the researchers found very few people who used a seat previously occupied by an infected person went on to become ill with the virus.
The researchers concluded that a safe social distance of more than one metre is required for one hour spent travelling together. After two hours of contact, they consider a distance of less than 2.5 metres to be insufficient in preventing transmission.
Professor Andy Tatem, director of WorldPop, said: “Our research is the first to quantify the individual risk of Covid-19 transmission on public transport based on data from epidemiological investigations of disease cases and their close contacts on high-speed trains.
“It 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.”
The findings suggest that during the pandemic, it’s important to reduce the density of passengers on trains and promote personal hygiene measures, including the use of face coverings, said Dr Lai. It might also be worth carrying out temperature checks before boarding.