COVID-19 patients hospitalized with the wild-type virus in 2020 were at a 29% higher risk for death than their nonhospitalized counterparts 3 years later, and even those with mild illness still reported new-onset health consequences, concludes a report on long COVID published today in Nature Medicine.
Researchers from the Veterans Affairs (VA) St. Louis Health Care System and Scripps Research followed up on 135,161 COVID-19 survivors and 5,206,835 controls in the VA system for 3 years to estimate the risks of long COVID and death. At the time that the survivors were infected, COVID vaccines and antivirals hadn't been developed.
There were 114,864 participants (12.0% women) in the non-hospitalized group and 20,297 in the hospitalized group (5.8% women). In the control group, 9.7% were women.
Even mildly ill patients prone to symptoms years later
The risk of death among patients hospitalized within 30 days of infection decreased over time but was still significantly elevated 3 years post-infection (incidence rate ratio, 1.29). Although the risk of long COVID declined over that time, substantial residual risk persisted, leading to 90.0 disability-adjusted life years (DALYs) per 1,000 people.
Among non-hospitalized patients, there was no increased risk of death after the first year, and the risk of long COVID declined over 3 years but still led to 9.6 DALYs per 1,000 people in the third year.
Three years post-infection, hospitalized COVID-19 patients had a 34% higher risk of symptoms across all organ systems than controls, down from an 182% increased risk 1 year post-infection and 57% at 2 years.
Over 3 years, 378.7 long-COVID symptoms were reported per 1,000 people, including 212.3, 125.0, and 41.2 in the first, second, and third year post-infection, respectively. This corresponded to 56.1%, 33.0%, and 10.9%, respectively, of the total 3-year long-COVID burden.
The 3-year burden of DALYs attributed to long COVID-19 was 91.2 per 1,000 people, including 54.3, 27.3, and 9.6 in the first, second, and third year, respectively. This corresponded to 59.6%, 29.9%, and 10.5%, respectively, of the total 3-year DALYs.
Total DALYs of hospitalized COVID-19 patients at 3 years (766.2 per 1,000 people) were 8.4 times higher than those of non-hospitalized participants (91.2 per 1,000 people).
There was a 5% increased risk of long-COVID symptoms at 3 years among non-hospitalized patients, which translates into 41 more health problems per 1,000 people. In comparison, the risk was 23% higher 1 year post-infection, rising 16% by 2 years. Persistent health effects in the third year mainly affected the gastrointestinal, lung, and neurologic systems.
Challenging notion of infection as short-term illness
"While risk declined over time in both people who were non-hospitalized and hospitalized for COVID during the initial phase of the infection, residual risk remains even in those who had mild COVID; that risk is much higher in the hospitalized," study author Ziyad Al-Aly, MD, chief of research and development at the VA St. Louis Health Care System, told CIDRAP News.
