A COVID-19 patient recovering at home in Brooklyn, New York, on November 21, 2020.
  • A new study tracked nearly 180 hospitalised Covid-19 patients in Florida for up to a year.
  • Adults with severe Covid-19 were twice as likely as uninfected people to die within a year.
  • Persistent inflammation may continue to jeopardise patients' health.
  • For more stories go to www.BusinessInsider.co.za.

Nearly 180 people left the University of Florida health system alive after being hospitalised with severe Covid-19 during the US's first wave of coronavirus infections. But within a year, more than half of those recovered patients had died, according to a study from University of Florida researchers published on Wednesday.

The researchers examined more than 13,000 patient records from January to June of last year, before vaccines were available. They identified 93 patients hospitalised with severe Covid-19 who died between one and 12 months after they were discharged from the hospital — a sign that long-term complications from the disease continued to jeopardise their health.

The study found that adults who recovered from severe Covid-19 were twice as likely as uninfected people to die within a year of contracting the disease.

"A lot of times when people have an infectious disease, they have it and then the episode ends and it's pretty much gone," Arch Mainous, the study's lead investigator, told Insider. But Covid-19 is different, he said: "Just because you get out of the hospital, it's not over."

Younger adults faced a particularly high risk of long-term health problems: Covid-19 patients under 65 who were initially discharged from the hospital were three times as likely as uninfected people to die within a year.

Adults older than 65 are more likely to succumb to Covid-19 quickly, so many won't ever reach the recovery stage, Mainous said. Younger adults, on the other hand, are more likely to survive an initial infection, then suffer from lingering symptoms for months, or perhaps years, to come.

"The internal trauma of having a severe Covid episode is manifested even more so in these young people," Mainous said.

Researchers aren't sure why Covid-19 patients are dying of long-term complications, but Mainous has a theory. Covid-19 may ignite a persistent inflammatory response, which wreaks havoc on a person's organs even after they've cleared the virus, increasing their risk of heart attack, pneumonia, kidney failure, or stroke.

"We believe that there's a huge inflammatory response which is systemic and that's why we don't see it localised only in one spot," he said.

Covid-19 wasn't listed as a cause of death for any of the deceased patients in his study, he added, which implies the disease may be even deadlier than available data suggests. A model from The Economist in May, for example, suggested that at least half the world's Covid-19 deaths hadn't been reported.

Persistent inflammation could damage the heart, lungs, or kidneys

Clinicians intubating a COVID-19 patient in the intensive-care unit at Lake Charles Memorial Hospital in Lake Charles, Louisiana, on August 10.

Severe Covid-19 generally results in three negative health outcomes, Mainous said: blood clots, respiratory problems, and cardiovascular issues.

January study in The Lancet found that up to 56% of hospitalised Covid-19 patients showed signs of lung problems six months after their initial Covid-19 symptoms.

Mainous' research team found in July that people hospitalised with severe Covid-19 were more than twice as likely as patients with milder Covid-19 to be hospitalised again because of health complications from the disease. Those complications included heart attacks, stroke, pneumonia, and pulmonary embolism — a blockage in a lung artery caused by a blood clot.

Chris Duncan, whose 75-year-old mother, Constance, died from COVID-19 on her birthday, photographing a COVID Memorial Project installation of 20,000 American flags on the National Mall on September 22, 2020, in Washington, DC.

Curiously, though, most hospitalised Covid-19 patients in the new study didn't die of cardiovascular, respiratory, or clotting problems. Instead, those conditions represented just 20% of deaths among hospitalised people who initially recovered from severe Covid-19.

Mainous said an aggressive inflammatory response in some patients could damage organs besides the heart and lungs, such as the brain, liver, or kidneys. 

"There may be some sort of organ system dysregulation that we didn't think about and that we're not monitoring," he said.

Getting vaccinated, he added, reduces the risk of winding up in the hospital in the first place. Covid-19 vaccines remain highly effective at preventing severe disease, hospitalisation, and death.

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