Scientists say public transport may not be a major source of coronavirus spread

By | August 3, 2020

Why the Tube or subway could be safer than you think: Scientists say public transport may not be a major source of coronavirus spread after all

  • Trains, buses and planes earmarked as potential Covid-19 hotspots early in crisis
  • But data from contact tracing studies suggest chance of catching virus minimal
  • Reduced use thanks to working from home thought to be partly behind low risk 
  • As is good compliance with face masks and social distancing, experts believe

Catching coronavirus on public transport is far less likely than once feared, fresh data suggests.

Trains, buses and planes were earmarked as potential Covid-19 hotspots by experts around the world at the start of the crisis.

This is because Covid-19 thrives in enclosed indoor spaces with little ventilation and densely packed crowds of people.

But research suggests that, if masks are worn and social distancing is adhered to, the chance of the virus spreading on public transport is minimal. 

Contact tracing studies looking into hundreds of Covid-19 clusters in France, Austria and Japan linked fewer than 1 per cent of ‘super-spreader’ events back to public transport.

The likelihood of catching the virus was found to be far higher when working in an office, eating at a restaurant or drinking in a bar.

Scientists say people tend to stay on trains or buses for relatively short periods of time and often do not talk to anyone, reducing the amount of aerosols they dispel.

Masks are also compulsory on public transport in most countries, which reduces the spreading risk further, whereas in most work environments and restaurants they are not. 

However, researchers concede that the data will be skewed by the fact fewer people are using public transport, even in a post-lockdown climate.  

And public health officials say tracking infection clusters to precise train carriages and buses is difficult, which may mean they are not appearing in the figures.

Catching coronavirus on public transport is far less likely than once feared, data suggests. Pictured:  Passengers on the London Underground this morning

Catching coronavirus on public transport is far less likely than once feared, data suggests. Pictured:  Passengers on the London Underground this morning

Scientists say people tend to stay on trains or buses for relatively short periods of time and often do not talk to anyone, reducing the amount of aerosols they dispel

Scientists say people tend to stay on trains or buses for relatively short periods of time and often do not talk to anyone, reducing the amount of aerosols they dispel 

Britons were told to avoid using public transport unless absolutely essential during the strictest days of lockdown, resulting in its use plummeting by around 90 per cent.  

Now, people in the UK can use the services whenever they please as long as they wear a mask or face covering.

But they are advised to travel at off-peak times, take less busy routes, use contactless payment to avoid touching others and keep one metre apart from other commuters.  

Pubs, restaurants and weddings are ‘super-spreading’ events 

Pubs, restaurants and weddings are three of the main sources of super-spreader events, SAGE scientists warned in May.

Experts advising the Government told ministers that thousands of Covid-19 clusters have been linked back to these ‘high risk’ settings in other countries where curbs have already been eased. 

In a report submitted to Number 10 in late May, SAGE said up to 100 people could contact the disease at one time in these places, even if just one person is Covid-19-positive.

They analysed clusters of cases around the world and highlighted bars, weddings, funerals, hotels, sporting events and shops among the riskiest areas of miniature outbreaks. 

Almost 70 per cent of all of South Korea’s new infections are happening at super-spreader events, the report said, and four in 10 cases are cropping up in these settings in New Zealand – two countries which have fended off major outbreaks.

It suggests that, even as the UK’s crisis seems to have subsided, there is still a high chance clusters can emerge at these events.  

SAGE’s report on super-spreader events recommended that testing be introduced at places where clusters could crop up – such as at pubs, concerts and football matches.

It reviewed thousands of super-spreader events seen in almost a dozen countries around the world – including the US, Australia, Japan and Germany.

The scientists identified 201 super-spreader settings, almost all of which were either purely indoors, where the virus lingers in the air and finds it easier to spread, or a mix between outdoors and indoors, such as weddings. 

The biggest clusters were most common in hospitals, care homes and cruise ships, where more than 100 people got infected at once.

But social events could see between 50 and 100 Britons catch the illness at once, even if just one person has Covid, SAGE warned.

In the report submitted to the Government in late May, researchers highlighted that up to 70 per cent of new infections in South Korea caught the virus at such events.

A similar theme was seen in New Zealand, where more than four in 10 new cases caught the disease in those settings. 

Writing in the report, SAGE said: ‘Rapid identification of clusters may be disproportionately important for control, e.g. large-scale testing and quarantine based on event/location could be contributing larger reduction than reconstruction of individual-level transmission chains via contact tracing.

‘Identification and prevention of clusters would be easier if most transmission occurs in predictable settings/situations.’  

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Contact tracers analysing 386 infection clusters between May and July in Paris found just four were linked to public transport (1 per cent). 

A cluster is defined as more than three cases that can be traced to a common event or venue. 

The study was conducted by researchers at Sante Publique France, the country’s national public health agency. 

A study of 297 super-spreader events in Austria in April and May by public health officials found none were related to public transport. 

Similarly, in Tokyo, where public health officials have aggressively hunted down and isolated infected patients’ contacts, none were linked to the city’s infamously overcrowded subways. 

Tohoku University researchers found the vast majority of the clusters were instead traced to gyms, pubs, live music venues and karaoke bars.

In Singapore, the co-chair of the nation’s Covid-19 taskforce, posted on social media last month that ‘the risk of spreading the virus in gatherings and social interactions is much higher than in public transport where people wear masks.’  

A similar picture is emerging in New York City, the world’s Covid-19 death capital, where more than 23,000 people have died from the virus.

Analysis of contact tracing data by former New York City Traffic Commissioner, Sam Schwartz, found that just 4 per cent of 1,300 virus hospital admissions in early May had used public transport recently.  

Experts believe the low infection rates on public transport are partly down to reduced use, good compliance with face mask and social distancing rules and regular cleaning of buses and trains.

‘Each of these things layers one on top of the other to make things safer,” said Dr. Don Milton, an environmental health researcher and aerosol transmission expert at the University of Maryland told the NY Times.

However, Crystal Watson, a senior scholar at the Johns Hopkins Center for Health Security, urged people to interpret the findings with caution.

She said that tracking infection clusters back to public transport was difficult because people often don’t remember the precise train carriage or bus they took weeks ago. 

England’s Chief Medical Officer, Professor Chris Whitty, warned in the early stages of the crisis that crowded trains were of particular risk for catching Covid-19.

He said this was especially true for the London Underground, which serves roughly 1.2billion passengers annually. 

His comments are thought to be based on a wealth of research showing that public transport exacerbated infections during flu outbreaks.

A 2011 study by the University of Nottingham found that those using public transport during flu outbreaks were up to six times more likely to get infected.  

But there is currently no publicly-available data in the UK around the risk of catching Covid-19 on public transport.

There has been no reported clusters and people were advised to return to work and use buses and trains if they need to this morning.

But London Underground trains were far from packed today as workers appeared to ignore the government’s drive to get back to work.

Passengers, some still not wearing face coverings, had plenty of space for social distancing as a few took the Jubilee Line into the city centre.

Boris Johnson had heralded today – the first Monday in August – as the day ‘work from home’ guidance ends and Britain should return to the office.

But almost five in six office employees will continue to stay at home despite the desperate drive to reignite the economy.

Commuters sat on the Tube on their phones and reading the newspaper this morning, with plenty of spare seats and only a few travellers forced to stand.

It is a world away from the usual jostle for a position at rush hour, when thousands of weary Londoners cram into all available spaces in the carriages.

On a typical morning before Covid-19 struck, about 1,124,825 would take the Tube between 4am and 10am.

But during the pandemic this plummeted by up to 90 per cent, with just 109,306 taking the network on the morning of May 29. MailOnline has contacted Transport for London for today’s figures.

London traffic data from TomTom shows congestion at rush hour this morning stood at just 22 per cent, down from 26 per cent last week and 52 per cent last year.

But Apple mobility trends, which is only available up to Saturday, suggests there are more people driving in London – up 10 per cent – while walking and transit are down 11 per cent and 29 per cent respectively.

A Mail audit of 30 of Britain’s biggest firms, representing 320,000 employees, found just 17 per cent of office-based staff would travel to work this week.

The PM said Britons could go back to the workplace at the ‘discretion’ of their employers and would no longer be advised to stay away from public transport.

But many businesses are not planning for most workers to return to offices until at least towards the end of the year, while the likes of Facebook and bank RBS said staff will not go back until 2021.

Just one firm surveyed, investment bank JP Morgan, had set a target for a substantial return to the office today – just 2,400 of its 19,000 staff.

The approach taken by white-collar workers is in stark contrast to building sites, warehouses, shops and restaurants where staff have been at their workplace for weeks. 

The Government has been criticised for failing to hammer home its back-to-work message.   

Kevin Ellis, chairman of accountancy giant PwC, which has 22,000 staff in Britain, said he believed his employees would only spend three or four days per week at work even after the pandemic.

It had 5,000 staff in its offices last week and he hoped to reach 11,000 by the end of this week.

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