In less enlightened times, an outbreak of a deadly virus was taken as a sign of God’s displeasure and would be accompanied by the persecution of an unpopular minority. It was less than a coincidence that the scapegoats tended to be those of whom the Church took a dim view: heretics, ‘witches’ (i.e. unmarried women) and, above all, Jews. How neatly it all fitted into an existing narrative.

The desire to fit the Covid-19 pandemic into a moral fable of what sinfulness means in a secular society has been palpable. One of the most puzzling features of the virus is the way in which it severely incapacitates certain people while leaving others virtually unscathed. It is unsettling to think that our fate could depend on the roll of a dice. We don’t want to believe in an invisible, indiscriminate killer. We want to find to find some logic.

In a society in which healthfulness means drinking plenty of water and avoiding carbs, we want to believe that we can avoid the worst effects of Covid-19 if we just the follow the rules. There is an almost medieval desire to believe that those who suffer must have brought it on themselves in some way.

Fortunately, this is not the Middle Ages. Conventional religion has lost its power and nobody is threatening violence against scapegoats. But we do have the quasi-religion of the NHS and a prejudice among some against those who are considered to be a ‘drain’ on it. In our supposedly enlightened times, smokers, binge-drinkers and fat people may not quite be heretics, but they are certainly seen by some as sinners.

Attempts to link the coronavirus to the deviants of the twenty-first century got off to a rocky start. There was an assumption that heavy drinking made people more susceptible to the virus, but this has not been proved and alcohol consumption does not seem to be a risk factor. A similar assumption about smoking fell apart in the most dramatic fashion when smokers were found to be less likely to be hospitalised with Covid-19. In the USA, efforts to carry last year’s vaping ‘epidemic’ into the Covid era have fizzled out for lack of evidence.

Only obesity remains. Dr Aseem Malhotra, author of The Pioppi Diet, made headlines recently when he suggested that Boris Johnson might have avoided a spell in intensive care had he not been ‘significantly overweight. Malhotra also claims that Covid-19 patients are ten times more likely to die from the disease if they suffer from conditions related to obesity. Although this notion has been debunked by the BBC’s fact-checking show More or Less, the Prime Minister seems to have taken heed.

According to James Forsyth’s column in the Times, Johnson has privately expressed a desire to be ‘much more interventionist’ on obesity once the crisis is over. It is not clear what this means in practice. We already have a sugar tax, and Public Health England has been spending the last few years contributing to the drive towards shrinking chocolate bars and taking the flavour out of food. More than £220 million of taxpayers’ money is spent on doomed efforts to control people’s waistlines in England alone.

Leaving aside the total failure of every anti-obesity policy to date, let us consider the government’s political motivation for finding a scapegoat for Britain’s relatively high Covid death rate. How convenient it would be if people believed that South Korea handled the crisis better because of its low rate of obesity and not because of its contact tracing capability and widespread use of face masks.

It has been clear from the outset that obesity is a risk factor for Covid-19 complications. The increased mortality risk is nowhere near the 1,000 per cent implied by Aseem Malhotra, but evidence from the UK suggests that obese people hospitalised with the disease are 37 per cent more likely to die from it and that morbidly obese people are twice as likely to die from it.

If you are of a liberal mind, you might say this is none of the government’s business. If people want to put themselves at greater risk from this or any other disease, that is their look out. The only reason to feel aggrieved would be if these people were clogging up hospital beds, draining our wallets and disgracing us in the eyes of the world. That was broadly the reaction to the Times’ story on social media this morning. A scapegoat had finally been found.

But the notion that coronavirus wards are rammed with obese people does not stand up against the facts. A study of Covid-related hospital deathspublished last week showed that 35 per cent of cases were obese. This is only slightly higher than the rate of obesity among certain groups of older people, and so suggests that the biggest risk factor, by far, is old age. The study found that you are 27 per cent more likely to die from Covid-19 if you have a body mass index (BMI) between 30 and 35. If you are over the age of 80, you are 1,200 per cent more likely to die from it (compared to people aged 50-60).

If Britain had fewer obese people it would have more old people. If it had more old people, it would have more deaths from Covid-19. Italy’s relatively low rate of obesity may have contributed to it having an unusually large elderly population, but this did not prevent it from having an unusually high death rate from Covid-19. Quite the reverse.

This is the lesson from health economics that refuses to be learned. We all have to die from something. If you avoid a ‘lifestyle-related’ disease, you will die from something else at a later date. Blame the obese if you must, but don’t fool yourself into believing that you would benefit personally if, by some miracle, Boris Johnson’s forthcoming interventions succeed.