Is social distancing still needed?
PUBLIC TRANSPORT IS EXCEPTIONALLY COVID-SAFE.
SOCIAL DISTANCING IN VEHICLES SHOULD BE an early RESTRICTION TO GO
Is all this really necessary?
The kids went back to school yesterday. The Ableman household is suddenly somewhat quieter (I say somewhat as, actually, only one kid went back: staggered return means we’ve got the other for a whole extra week).
This was the first in a gradual relaxation of lockdown.
But in the whole sequence of stages from now to 21st June, it’s not entirely clear what the Government’s attitude is to social distancing on vehicles.
I’m certainly not going to go all Piers Corbyn by arguing that Covid isn’t serious or that the Government has no place seeking to manage risk.
However, in the 10 months since the pandemic began, we’ve learned enough about how Covid spreads to tell us that when rules start to be eased, capacity limitations on public transport should go early.
Now, the data in this article is all based on the previous variant of Covid, so I fully recognise the mutation may be different. But what this data tells us is that during the period before the mutation, public transport was a lot safer than the public messaging suggested.
If this holds true for the new variant, then social distancing on transport should be one of the first restrictions to be withdrawn - supported by clear messages that transport is safe.
The best article to bring it all into one place is this tour de force from The Atlantic. It’s long but if you have time, do read it.
It gets deep under the skin of how Covid spreads and reveals that Covid is characterised by rare but dangerous super-spreading events. Most infected people don’t infect anyone else but a handful infect lots. The R that we hear about is an average but it’s an average of many very low numbers and a few very high ones.
Why does this happen? Because certain environments are primed for Covid transmission. This brilliant article from El Pais presents it more clearly than anywhere else I’ve seen.
The rows show the number of infections respiratory particles a person will shed when silent, talking or shouting; while the columns show 2 mins, 15 mins or an hour.
2 minutes 15 minutes. 1 hour
This graphic was produced before the new Kent super-virus came into existence, so the precise numbers are out of date but the principle is unlikely to be.
What this graphic shows is that a person shouting or singing for an hour will release 1,500 infectious doses, against 8 for someone silent for 15 mins. This explains why certain people are super-spreaders. If Uncle Nigel comes round to your place and spends an hour ranting about politics, he’s going to release 187 times as many infectious particles as someone sitting silently on public transport.
This is why Japan, which has managed to have a staggeringly low infection rate despite never introducing a full-scale lockdown, promotes the three Cs as the key risk factors; Closed spaces with poor ventilation; Crowded places with many people; and Close-contact settings such as conversations.
When you think of public transport you immediately think all three apply. But they don’t.
A closed space, in virus terms, means a small, enclosed room - such as your front room. A typical train or bus is many times the size of most peoples’ private accommodation and most people keep their homes sealed (hence ‘enclosed’). By contrast, most public transport air con systems completely refresh the air on a regular basis.
THIS is a close-contact, crowded setting.
Photo credit: Ann Larie Valentine, FlickrAnd there are no close-contact settings on public transport. In this context, close contact means conversations. Look up the page at the El Pais gif and see just how much less likely a silent person is to transmit virus than someone speaking. There are few places where Brits are less likely to talk than on public transport! And time spent together is also fundamental: with the average bus journey being around 4 miles, people spend much less time together than in hospitality settings.
And finally there are masks. Back in June, Goldman Sachs decided to try to calculate the value of face masks. Characteristically for Goldman Sachs, they focused on the impact of masks on GDP not on lives saved. But the evidence was overwhelming: masks make a big difference. And public transport is an environment in which masks are universal.
Japan is the exemplar for this entire approach. Since March, their Government has focused rigorously on the 3Cs. The Economist quotes (paywall) Nishimura Yasutoshi, the Japanese minister responsible for Covid response, as saying that even crowded subway trains pose little risk. In Japan, use of public transport is close to normal levels, and infection rates are a fraction of rates in the UK. That’s not because the epidemic is hidden, as deaths can’t be missed and the death rate is on a different scale. This is like-for-like as it dates from before the spread of the Kent variant:
Graph from Financial Times (www.ft.com) This is because Japan is focused on super-spreading environments, which do not include public transport. The Japanese Government advises people to avoid five very specific settings where transmission is most likely:
dinner parties with alcohol;
drinking and eating in groups of more than four;
talking without masks at close quarters;
living in dormitories and other small shared spaces;
using changing or break rooms.
None of these apply to public transport. (The first four all apply to family Christmas celebrations, which is why cancelling Christmas was probably a good idea, even if taken idiotically late)
If the Japanese experience was not sufficient evidence, there have also been studies of the Covid risk by regulators around the world. In the UK, the RSSB concluded as long ago as July that the risk of transmission on a full train was 1 in 11,000 - and this could be further halved by face coverings. Similar conclusions were reached by the Robert Koch institute in Germany; generally considered one of the world’s most respected public health agencies.
However, you could argue that all of these studies are theoretical. They’re based on the characteristics of the virus as we now understand it, and what that is likely to mean for infection. But given how long the pandemic has been going on, surely we now have enough data to understand what has actually happened in reality - and not just in Japan.
Well, yes, we do. The Economist has taken estimates of the “R” reproduction rate from 334 British local authorities and correlated them with movement data from mobile phones to see what behaviours caused infection to spread in the real world. Their conclusion (paywall):
Usage of parks or public transport had no impact, perhaps because visitors are outside or wearing masks
So, we’ve established that:
The characteristics of the way Covid spreads means a public transport environment is unlikely to cause transmission
Correlation data shows that public transport isn’t associated with increased transmission
But what would be absolutely ideal is if we also had a ready-made case study: an environment that replicated what public transport would look like if social distancing was abolished.
Well, we have. The airlines have refused to play ball with social distancing throughout the pandemic. The evidence suggests that, as per Goldman Sachs’ research, that masks are key. This New Scientist article reveals that almost exactly a year ago, an infected couple travelled for 15 hours with 350 fellow passengers. All wore masks; no transmission occurred. The New Scientist quotes the Massachusetts Institute of Technology as finding the infection risk from a full flight in the UK as being 1 in 4,000 and the risks in the UK to be 10 times lower. Now this extraordinarily low risk is partly caused by the quality of air filters on planes which are not universal on public transport. But it is primarily caused by the fact that planes, like trains and buses, are not super-spreading environments.
As long ago as October, IATA produced a study that got widespread coverage that showed that someone would need to travel for 54 hours on a plane to get infected with Covid.
Now, this study was scientifically dubious and patently self-serving. But it was demonstrating a truth for which evidence is widespread: seated, quiet, masked passengers travelling together are a very low risk for Covid transmission.
Everyone in face masks, high utilisation but little talking. Compare this photo with the El Pais graphic at the top, and the picture of the dinner party.
Now we know this, it’s time for the trade bodies for public transport (and individual firms) in the UK to start acting like IATA and seeking the evidence to abolish social distancing as soon as restrictions start to ease. This should include commissioning research on the behaviour of the new variant and testing whether the Japanese style approach remains valid (I suspect it does). Public transport needs to be confident in its safety, not because we don’t understand the risks, but because we do.
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