MADRID, July 18 (EUROPA PRESS) –
The risk of developing long-term COVID-19 illness has significantly decreased throughout the COVID-19 pandemic, according to an analysis of data from Washington University School of Medicine in St. Louis, US. The study is published in the New England Journal of Medicine.
The researchers attributed about 70% of the risk reduction to COVID-19 vaccination and 30% to changes over time, including the evolutionary characteristics of the SARS-CoV-2 virus and improved detection and treatment of COVID-19. “The study of the decline in COVID-19 cases is one of the rare times I have good news about this virus,” said lead study author Dr. Ziyad Al-Ali, a clinical epidemiologist at the University of Washington and a world leader in COVID-19 research. “The results also show a positive effect of vaccination.”
In more than 30 high-profile studies, Al-Ali has detailed the virus’s indiscriminate, long-term health impacts on nearly every organ system, affecting the heart, brain, kidneys, and gastrointestinal tract.
While his latest findings sound more encouraging than previous studies, Al-Ali tempers the good news. “Long COVID is not over,” says the nephrologist, who treats patients at the John J. Cochran Veterans Administration Hospital in St. Louis, an affiliate of Washington University. “We can’t let our guard down. That includes getting the COVID vaccine every year, because that’s the key to suppressing the risk of long COVID. If we stop getting the vaccines, the risk will likely increase.”
Since the beginning of the pandemic, Al-Ali has dedicated himself to analyzing long-term COVID to help the public make informed health decisions; support scientists in developing research-based recommendations for prevention and treatment; and enable policymakers to make informed decisions about funding and public policy. Al-Ali’s latest research builds on this work by examining variants of the virus and their overall evolution.
To do this, Al-Ali and his team analyzed millions of anonymized medical records from the U.S. Department of Veterans Affairs, the largest integrated health care system in the country. The study included 441,583 veterans with SARS-CoV-2 infection and more than 4.7 million uninfected veterans from March 1, 2020, to January 31, 2022. The patients varied in age, race, and gender; a statistical model ensured parity in representation.
The researchers divided the veterans into five groups: unvaccinated COVID-19 patients who contracted the original strain in 2020; the delta variant in 2021; and the omicron variant in 2022. The other two groups included vaccinated people who had the delta variant and people vaccinated with the omicron variant. There were no vaccines available while the original strain was circulating. The team assessed the incidence of long COVID a year after infection for each of the five groups.
As expected, the rate of long COVID infection was highest among those with the original strain, with 10.4% of those whose infection progressed to long COVID, Al-Ali said. That figure dropped to 9.5% among unvaccinated groups during the delta era and 7.7% during the omicron era. Among those vaccinated, the rate of long COVID cases during the delta variant was 5.3% and 3.5% during the omicron variant.
“You can see a clear and significant difference in risk in the delta and omicron era between vaccinated and unvaccinated people,” Al-Ali says. “So if people think COVID is not a big deal and decide to forego vaccines, they are essentially doubling their risk of developing long-term COVID.”
Al-Ali also stresses that even with the overall reduction, a rate lower than 3.5% remains a significant risk. “That means for every 100 people vaccinated, three to four people will develop persistent COVID,” he says. “When you multiply that by the large number of people who continue to get infected and re-infected, that’s a lot of people. That remaining risk is not trivial. It will continue to exacerbate an already alarming health problem that people around the world are facing.”
Another notable finding provides insight into the evolution of the virus, Al-Ali adds. When analyzing the risk among all people infected with COVID-19 in the omicron era of 2022, the likelihood of developing problems with the heart, brain, kidneys, and lungs decreased. In contrast, the incidence of diseases and illnesses related to metabolic function and the gastrointestinal system increased.
“People tend to think of SARS-CoV-2 as a uniform virus,” insists Al-Ali. “But each variant has its own signature. The original virus heavily targeted the respiratory system. Omicron targets metabolic and gastrointestinal issues. This is important because while the risk of long-term COVID is quantitatively lower, a person may be at higher risk of developing the disease depending on which part of the body the COVID variant attacks.
“It’s very good news that the risk has gone down,” he says. “But we know that millions of people are already suffering from persistent COVID-19, and that millions more will continue to suffer from it. We need to redouble our efforts to understand this so that we can prevent suffering and treat those affected.”