Is there any evidence that closing bars at 10 p.m. will stop the spread of the coronavirus?

It seems that every aspect of Covid-19 will be contested. Students of the history of public health politics will be having a strong sense of deja vu: the field is littered with heated debates that in essence are about numbers.

As someone who has worked in the field of tobacco control for some 40 years, I have witnessed many such debates. First, there was the question of how risky smoking was; then the addictive nature of tobacco. There were questions over how much safer low-tar cigarettes were. Then, of course, there was the issue of the harmfulness of passive smoking. Most recently there was the claim that e-cigarettes were 95% less harmful than “normal” cigarettes.

To my mind these tobacco control dramas have had one important thing in common: a failure of some of those involved to use numbers as a way to achieve clarity. Instead vague quantification shapes a narrative. And that is exactly what we are seeing in the evolving arguments about the coronavirus.

A recent act in this pandemic drama centres on the policy of forcing bars and restaurants in England to close at 10pm. The prime minister claimed to have based this new rule on scientific evidence that much of the spread of the virus is taking place in bars late in the evening. He says that this is at least in part due to people having consumed quite a bit of alcohol by this time and so being less likely to respect social distancing rules.

This raises an important question. Does the government have a concrete estimate of the likely number of infections, hospitalisations and deaths averted by closing bars at 10pm? If so, what is the margin of error and what is the science on which it is based? Speaking personally I cannot recall the behavioural science subgroup of Sage – of which I am a participant – ever being asked about this. On a matter of such importance I would have expected advice to be sought, because the policy depends very largely on how people behave.

If behavioural scientists had been asked to provide input into an estimate of the impact of the 10pm bar closures, one source of available evidence would be the extent to which allowing bars to remain open later at night in England and Wales back in 2005 made any difference to alcohol consumption or binge drinking. This would provide at least some evidence as to what might happen if one were to now restrict licensing hours.

The answer appears to be that the impact was minimal. This may be for reasons that are not particularly informative in the current scenario. But it points to the possibility that restricting licensing hours would have a limited impact on how people behave later into the night. Other evidence suggests a more worrying conclusion: it seems that during the pandemic there has already been an increase in the proportion of alcohol that is consumed not in licensed premises. This might lead to concern that closing bars at 10pm would not reduce risky social contacts but might increase it, as people take their drinking to other locations.

These impacts are quantifiable, albeit imprecisely. For example, I would judge the effect of the 10pm curfew on the infection rate to range between a reduction of around 10% and an increase of around 10%. Others might disagree, but we could then discuss this in concrete terms. Without being forced to state the range, we cannot get a handle on where any points of disagreement might lie in a scientific sense, and so the arguments can easily descend into polemics.

The impact on the infection rate is just one number we are interested in when it comes to what to do about high-risk venues such as bars and restaurants. Another important number to estimate is the potential loss of income for venues in forcing them to close earlier. With so much at stake, I would expect a responsible government to seek advice on the likely range of values for this number, and for it to be thoroughly examined.

Unless policymakers engage with numbers as concrete statements of what can be expected, there is no basis for rational decision making; and discussion about whether a policy is right or wrong is, in the language of the Scottish play, little more than strutting and fretting, “signifying nothing”.

Perhaps the government is putting numbers into its ever-changing patchwork of policies, and perhaps it is comparing best-case and worst-case scenarios. Maybe it is consulting widely among experts and stakeholders who can help inform its estimates. I would put the likelihood of that to be somewhere between 1% and 5%.

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