Transport systems low risk for spreading Covid, London Underground data shows

Passengers can expect lower chances of infection if they are able to follow lockdown mitigation measures

The London Underground kept mask-wearing rules when most other national mask mandates were lifted last year. Reuters

Public transport systems present a low risk for the spread of Covid-19 if the network has good ventilation and preventive health rules, computer simulations based on London Underground data have shown.

Commuters from Lisbon to Beijing can expect a lower chance of infection if they are able to follow the best practices offered by lockdown guidance, such as social distancing, the report published on Tuesday shows.

Risk on public transport is reduced when passengers wear a face covering, maintain a 2 metre distance, sanitise hands and encourage people with symptoms to stay at home, according to computer modelling carried out by the University of Leeds, the UK's Defence Science and Technology Laboratory and the University of Manchester.

They used pre-pandemic data from the London Underground in their models.

The British capital's 'Tube' system is infamous for its lack of air conditioning but has some windows that can help with ventilation, while mask use during lockdown periods has been varied.

“All environments where people interact together have a risk of virus transmission and public transport is no exception,” principal investigator Prof Cath Noakes said.

“Where journeys are short and not overcrowded and the carriage is well ventilated, then the risks are likely to be quite low.

“Wearing a face covering can significantly reduce risk of the virus spreading, particularly as it can be harder to socially distance in a Tube or subway carriage at certain times of the day.

“The results show that compliance with good mitigation measures is likely to be effective in reducing infection."

The computer models, carried out before the emergence of the Omicron variant, simulated the risks of people being exposed to the virus through the main routes of transmission.

Writing in the journal Indoor Air, the researchers said: “To date there is no evidence that public transport is a major driver for the pandemic but as a shared enclosed setting where people may be at close proximity, transmission is possible and understanding the factors that influence the likelihood of transmission is important for introducing and managing effective mitigation strategies.

“This is particularly important as public transport is a necessity for many people, and it can be an environment where social distancing is difficult to maintain, particularly in dense urban transport systems.”

Prof Noakes believes the mitigation measures will continue to reduce the chances of infection, even with the Omicron strain.

“The Omicron variant is more transmissible and the risks of exposure in different settings including on public transport are not yet clear. However, the mitigations identified in the study are still likely to be effective at reducing the risk of exposure to the virus.”

The research underlined the effectiveness of continuing with well-established mitigation measures — social distancing, widespread mask use, working from home and sanitising hands.

Dr Martin Lopez-Garcia, a mathematical modeller from the University of Leeds and co-author of the paper, said: “Our model provides an insight into the different factors that are likely to influence risk and should be used to effectively plan strategies that reduce the transmission of the virus.”