Dr Muiris Houston: Beware the long tail of Covid-19

Even a mild case of the virus can increase the risk of cardiovascular problems

With mandatory mask-wearing coming to an end and the National Public Health Emergency Team being stood down, does this mean the coronavirus pandemic has ended? It’s far too early to say, especially for certain groups such as the immunocompromised, but it does mark an appropriate moment to consider the long-term effects of Covid-19.

Long Covid or post-Covid syndrome is something we have known about since early in the pandemic. But now evidence is mounting to suggest that SARS-CoV-2 infection causes specific disease in a number of body systems. This is something we have seen historically with previous infections such as TB and HIV. Morbidity inevitably stalks mortality, but tends to attract less headlines. So the narrative for most is that Covid-19 is something from which a small number of people die, and that most of us bounce back quickly, with no long-lasting effects.

However, a large study published last week in the journal Nature Medicine showed that even a mild case of Covid-19 can increase a person's risk of a wide range of cardiovascular problems for at least a year after Covid diagnosis. Researchers found that rates of many conditions, including heart failure, heart attack and stroke, were substantially higher in people who had recovered from Covid-19 than in similar people who hadn't had the disease.

Dr Ziyad Al-Aly and his colleagues from Washington University in St Louis Missouri based their research on an extensive health-record database held by the US Department of Veterans Affairs. The researchers compared more than 150,000 military veterans who survived for at least 30 days after contracting Covid-19 with two groups of uninfected people: a group of more than five million people who used the VA medical system during the pandemic, and a similarly sized group that used the system in 2017, before Sars-CoV-2 was circulating.


People who had recovered from Covid-19 showed sharp increases in 20 cardiovascular problems in the year after infection. For example, they were 52 per cent more likely to have had a stroke than the contemporary control group, meaning that, out of every 1,000 people studied, there were about four more people in the Covid-19 group than in the control group who experienced stroke.

The risk of heart failure increased by 72 per cent, or about 12 more people in the Covid-19 group per 1,000 studied. Hospitalisation increased the likelihood of future cardiovascular complications, but even people who did not require hospital admission were at higher risk for many conditions.

“It doesn’t matter if you are young or old, it doesn’t matter if you smoked, or you didn’t,” Al-Aly says, “the risk was there.”

Commenting on their results, the authors point to two key findings: “That the risks and associated burdens were evident among those who were not hospitalised during the acute phase of the disease – this group represents the majority of people with Covid-19; and that the risks and associated burdens exhibited a graded increase across the severity spectrum of the acute phase of Covid-19 (from non-hospitalised to hospitalised individuals to those admitted to intensive care).”

While acknowledging the observational nature of their research, Al-Aly told Nature that healthcare providers around the world should be prepared to address an increase in cardiovascular conditions. But with high Covid-19 case counts still straining medical resources, he is worried that health authorities will delay preparing for the pandemic’s aftermath for too long.

He is right to be concerned. History shows how bad we are at responding to the long-term effects of acute infections. Once a vaccine for polio was discovered, the debilitating epidemic was forgotten. And, when, decades later, a proportion of the survivors of those epidemics relapsed – with post-polio syndrome – their condition failed to elicit the same level of concern.

Let’s not repeat the same mistakes with Covid-19.