Covid-19 is really a syndemic — and that shows us how to fight it

Covid-19 is really a syndemic — and that shows us how to fight it

The writer is a science commentator

Here’s some uplifting news: we are no longer in a pandemic. There is, alas, a catch: we are instead trapped in a “syndemic”.

A syndemic, or synergistic epidemic, refers to the idea that the virus does not act in isolation, like a lone villain dispensing pneumonia and organ failure with even-handed cruelty across the population. Rather, it has accomplices, such as obesity, diabetes and heart disease, that compound the damage.

Each accomplice is already a standalone epidemic and these familiar diseases often go hand in hand, a Cosa Nostra of co-morbidities. Obesity, for example, is a risk factor for developing diabetes and heart disease. But pair any, or all, of them with Covid-19, and a patient is plunged into syndemic territory, where joint enterprise magnifies clinical danger. A recent paper in the journal Obesity Reviews concluded obese people were nearly 50 per cent more likely to die from the virus than non-obese peers. 

This messy tangle of interacting epidemics is why we should consider Covid-19 a syndemic, according to Richard Horton, editor of the Lancet medical journal, who argues against a narrow “plague” narrative in a recent editorial.

“Focusing on the virus alone is a mistake,” he told me, of the single-minded pursuit of Covid-19 treatments and vaccines. The deadly impact of the pandemic “is not caused by the virus acting alone but interacting with chronic diseases like diabetes, obesity, heart disease and high blood pressure — all against a background of inequality and poverty. We can’t fully control the infection without addressing those factors.”

Doesn’t expanding the coronavirus pandemic into a syndemic widen the problem and induce a greater sense of hopelessness? Mr Horton claims the opposite as “it gives you a whole range of measures to implement right now to protect people while we wait for a vaccine”. His basic prescription is to tackle those familiar epidemics: cut obesity, improve the treatment of diabetes, heart disease and cancer, among other illnesses. That means paying attention to keeping health systems afloat for other conditions.

Obesity was a risk factor for both UK prime minister Boris Johnson and US president Donald Trump in their illnesses. The UK government unveiled a new obesity strategy in July, with promises to stop multi-buy offers on unhealthy foods and clamp down on junk-food advertising. But that feels like nibbling at the edges of a meatier problem that Mr Horton and, most notably, epidemiologist Michael Marmot have identified: the influence of poverty and inequality on health.

In high-income countries, obesity is increasingly seen as a disease of the poor. Type 2 diabetes also clusters in deprived communities. Covid-19 is finding a foothold in the same places. While age is the biggest risk factor — among those in the UK testing positive in the first wave, over-80s were 70 times more likely to die than under-40s — deprivation matters. Covid-19 death rates in the UK’s most deprived areas are more than double those in the least, according to the NHS and Public Health England. 

Possible reasons include cramped housing, which makes isolating and quarantine difficult; higher exposure in public-facing occupations, such as in health and social care, delivery and retail; reliance on public transport; and, of course, pre-existing poor health.

Compare that with the experience of more affluent workers, sitting out the pandemic at laptops in comfortable homes or switching to private cars for the commute. This crisis has broadly separated us into the exposed poor and the shielded rich. Covid-19 is widening, not closing, health gaps. 

That worries the Health Foundation, a UK charity, which noted this week that the poorest local authorities experienced more severe financial hardship alongside higher death rates. That grim double whammy to wealth and wellbeing has especially hit black, Asian and minority ethnic communities. The charity launched an inquiry into Covid-19 health disparities, with Sir Michael advising, to report next summer. 

One notable figure who approves of the syndemic argument is Merrill Singer, the medical anthropologist at the University of Connecticut who coined the word in the 1990s and thinks it captures the social forces at play. “It means we have to consider not just biological issues but the social structural forces that propel disease interaction, population vulnerability and unequal access to healthcare, including, once we have them, Covid-19 vaccines.”

There is much talk of a post-pandemic resetting of the economy. Paying key workers more fairly would help to remedy the health disadvantages that stem from penury. But, Professor Singer warns, there will be a familiar obstacle blocking the path to equality: “a vested interest in the benefits of the status quo for the wealthy minority”.