MISSOURI – The risk of new disease, disability and death remains elevated in some patients as long as two years after catching Covid-19, according to a large study showing the infection’s prolonged heath impact.

People who were never sick enough to be hospitalised for acute Covid-19 still had a higher risk than uninfected people of developing long Covid-related disorders such as dangerous blood clots, diabetes and lung, gastrointestinal and musculoskeletal disease two years later, according to the study published Monday in the journal Nature Medicine.

Some 65 million people globally are estimated to be living with so-called post-Covid-19 condition – a number reported to be steadily increasing in the absence of approved treatments and continuing viral spread.

The research from the Clinical Epidemiology Centre of the Veterans Affairs (VA) St Louis Health Care System in Missouri shows how long-term ailments that afflict Covid-19 survivors add to the disease burden of the pandemic.

“While many people’s long Covid symptoms improve slowly over time, this can take years, and some symptoms persist even beyond that point,” said Dr Michael Peluso, an assistant professor of medicine at the University of California, San Francisco. “The disability attributed to these post-Covid conditions is sobering.”

Long Covid has been linked to more than 200 symptoms affecting every organ system.

Epidemiologist Ziyad Al-Aly and his colleagues used the VA’s national databases to compare the incidence of 80 post-acute health problems among 138,818 veterans who survived the first month of a Covid-19 infection during the first year of the pandemic with almost six million who were not infected during the same period.

Those who were not hospitalised for Covid-19 had an increased risk of developing 31 per cent of the 80 ailments after two years of follow up, compared with non-infected controls, while hospitalised Covid-19 patients had a higher chance of developing 65 per cent of them.

“It’s very clear that people hospitalised during the acute phase of a Sars-CoV-2 infection have a really long and arduous road to recovery,” Dr Al-Aly said in an interview. “They have a significantly higher risk of death, even at two years.”

The increase in mortality risk from Covid-19 was not significant beyond six months for non-hospitalised patients, but remained significantly elevated through the two years for those who had been hospitalised, the study found. Most users of the VA health system are older males, which might limit how applicable the study’s findings are to other groups, the authors said.

Lasting damage

A severe case of Covid-19 may cause long-lasting alterations to the innate immune system, the body’s first line of defence against pathogens, researchers said on Friday in a separate study that points to why the disease can cause persistent inflammation and widespread organ damage.

Yet, another study published on Monday found Covid-19 may trigger new-onset hypertension, especially among hospitalised patients.

The VA study measured the burden of disease from long Covid-19 in disability-adjusted life years, or years lost due to disability.

Cumulatively at two years, long Covid contributed a burden of 80.4 disability-adjusted life years for every 1,000 people who caught Covid-19 but were not sick enough to be hospitalised, and 642.8 disability-adjusted life years for every 1,000 patients who were hospitalised for acute illness.

The disability burden “is extremely high, even in the non-hospitalised group, and shows the severity of the impact long Covid-19 is having and will continue to have on society”, said Ms Hannah Davis, who co-founded the Patient-Led Research Collaborative, which studies long Covid-19, after she developed the condition herself in early 2020.

The “timely and very important analysis” from the VA researchers confirms what doctors have heard from patients in the clinic and in smaller studies, UCSF’s Dr Peluso, who is also studying Covid-19’s effects, said in an e-mail.

More research is needed on the long-term risks associated with Covid-19, he said.

“It also reinforces the urgency of figuring out exactly what beyond the initial infection causes these post-acute symptoms and sequelae so that we can identify treatments to return people to their regular health sooner and minimise ongoing disability,” he said. BLOOMBERG