If social distancing works, why doesn’t it stop the virus spreading?

The evidence is beginning to mount that even voluntary social distancing (as well as lockdowns) may only have a limited effect against the coronavirus, challenging previous assumptions about the virus’s transmission and raising more questions about the point of some policy interventions.

In my last post I noted how infections had grown exponentially in Manchester and the North West even as Mancunians were busy avoiding one another, and that the growth had carried on for a full week after lockdown and a good two weeks after social distancing had begun. This is all the more striking for the difference from the London experience where the virus struck and peaked earlier.

How were so many Mancunians still picking up the bug when they weren’t going near each other?

This finding is not unique to Manchester: the same effect has been noted, for example, in Seattle, where infections grew exponentially for over two weeks while social distancing was in effect, from March 5 to the peak on March 20. The chart below starkly shows how little relationship there is between populations practising social distancing and the spread of the infection.

Source: www.moovit.com (transit data); government websites (death data). Notes: 1) Infections are assumed to occur on average 16 days before death (based on 6 days incubation and 10 days between symptoms and death); 2) Social distancing is assumed to correspond to use of public transport.

A new survey from New York State reveals the same odd phenomenon at work: of those in hospital with Covid-19 at the start of May, two-thirds had contracted the illness, not while out and about as a key worker, but while observing social distancing at home. The state governor described this as a ‘surprise’.

It certainly is. That New Yorkers, like Brits, are still catching the virus while stuck in their houses over a month after lockdown began is not what many experts expected.

With strict lockdown in force and being conscientiously observed by Brits, Professor Neil Ferguson predicted on March 25 that UK deaths would now not exceed 20,000. Yet as of May 8 they stand at 31,241 and counting (though at a much reduced rate). Lockdown clearly did not have the envisaged effect.

Quite how people are still catching the virus while staying at home is yet to be fully explained.

The mystery deepens when we consider the testimony against social distancing given by Dr Muge Cevik, an infectious diseases researcher at St Andrews University. She points to numerous research studies which suggest you can catch the Wuhan coronavirus only via a prolonged exposure to an infected person (my italics) making a nonsense of social distancing rules that aim to prevent passing contacts.

‘Casual, short interactions are not the main driver of the epidemic,’ she says. However she points out that ‘while we have limited data, high-risk transmission pattern seen in households, family and friend gatherings, could also be observed in other crowded and connected indoor environments such as crowded office spaces, other workplace environment, restaurants/cafes, public transport, and even in shopping centres etc where people often spend long periods of time and use shared facilities’. These observations would seem to lend some weight to Richard North’s speculation ‘that the virus could be deadlier if it spreads within families in the same house because of the prolonged close contact, thus hinting at the multiple exposure phenomenon.’ Closer investigation is required.

The need for prolonged exposure to catch the bug also supports the assumptions of the model developed by the Liverpool School of Tropical Medicine. This envisages collective immunity emerging at 10-20 per cent owing to varying susceptibility in the population. Part of this is due to pre-existing resistance to other ‘common cold’ coronaviruses, now shown to be present in up to a third of the population.

Meantime, after stating in my last post that there were no countries not observing social distancing (including Sweden), I have now come across one: Belarus. Belarus has not only not locked down but has also not banned any gatherings while all shops, restaurants, churches, schools and so on have stayed open. While there is some evidence of voluntary social distancing, it is despite rather than because of government advice, and the annual Victory Day celebrations went ahead as usual on Saturday.

Notwithstanding this striking defiance of international advice and expectations, the country of 9.5million people (a similar population to Sweden) so far has reported only around 120 deaths, with cases appearing to peak just under a week ago, suggesting deaths will peak soon. A country to watch, then, for evidence about whether social distancing is necessary to prevent catastrophe.

None of this amounts to firm proof against the value of social distancing, and there are yet more mysteries to be solved, such as how people are getting a virus requiring prolonged exposure while confined to their homes. To that we now have a possible and quite simple answer – that it’s closeness and prolongation of contact between the same limited number of people (family members) that may be the critical variables. Which by and large is not the experience of public transport.

But it does challenge the lazy assumption that our extreme responses to this outbreak are responsible for bringing it under control, rather than, as many epidemiologists such as Knut Wittkowski and Johan Giesecke argue, the virus simply running its course. All the more reason to study these things thoroughly and properly, so we can ensure that our measures now and in the future are proportionate and effective, and not a whisker more ruinous or oppressive than absolutely necessary.

First published on Conservative Woman.

One thought on “If social distancing works, why doesn’t it stop the virus spreading?

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  1. Because the virus has a long incubation period, would it not make sense that social distancing would not take effect for a couple of weeks and in any event it would depend on the extent of social distancing which might not be easily measured. In my home state of Kansas, the grocery stores are as frequented as ever and maybe half of folks are wearing masks but there is plenty of contact among people even if briefly while passing.

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