You’re far less likely to develop Long COVID now than you were in the midst of the pandemic, promising new data shows.

Changes in strains of SARS-CoV-2, the virus that causes COVID-19, are playing a role in the lowered risk, but so are the proven benefits of vaccination, the study authors said.

“The research on declining rates of long COVID marks the rare occasion when I have good news to report regarding this virus,” said senior study author Dr. Ziyad Al-Aly. “The findings also show the positive effects of getting vaccinated.”

Al-Aly is a clinical epidemiologist and COVID-19 research specialist at Washington University in St. Louis. His team published its findings July 17 in the New England Journal of Medicine.

The new report comes on the heels of another study published recently by a team at the University of Münster in Germany. That research found that risks for Long COVID declined with the emergence of each new successive strain of the virus, and with multiple vaccinations.

In the latest report, Al-Aly’s team pored over millions of health records compiled by the largest health care system in the United States, the U.S. Department of Veterans Affairs.

In total, the data included 441,583 veterans who’d been diagnosed with SARS-CoV-2 infections and more than 4.7 million uninfected veterans, tracked from March 1, 2020, through Jan. 31, 2022.

The researchers then divided the veterans into five groups.

First were three groups of unvaccinated veterans who became infected with COVID-19 with either the original strain in 2020, the Delta variant in 2021 or the Omicron variant that arose in 2022 (and continues today).

As well, the team separated out two other groups: Vaccinated people who had been infected with the Delta variant and vaccinated people infected with Omicron.

The researchers then looked at rates of Long COVID occurring within one year of infection among veterans in all five groups.

One clear trend emerged: Rates of Long COVID declined as each new strain emerged.

Overall, 10.4% of folks who’d been infected with the original strain of COVID-19 went on to develop Long COVID. However, that rate declined to 9.5% of those infected during the Delta era and 7.7% of those infected by Omicron.

Being vaccinated cut the odds for Long COVID even further: 5.3% during the Delta era and 3.5% once Omicron took over (vaccines were not available during the ‘original strain’ era of the pandemic).

“You can see a clear and significant difference in risk during the Delta and Omicron eras between the vaccinated and unvaccinated,” said Al-Aly, who is also director of the Clinical Epidemiology Center at the VA St. Louis Health Care System. “So, if people think COVID is no big deal and decide to forgo vaccinations, they’re essentially doubling their risk of developing long COVID.”

Al-Aly also stressed that the current risk of developing Long COVID (3.5%) is still substantial.

 “That’s three to four vaccinated individuals out of 100 getting long COVID,” he said in a university news release. “Multiplied by the large numbers of people who continue to get infected and reinfected, it’s a lot of people. This remaining risk is not trivial. It will continue to add an already staggering health problem facing people across the world.”

He stressed that, according to the research, the nature of Long COVID cases is also changing with each new viral strain.

For example, the advent of the Omicron strain appeared to coincide with a decline in Long COVID complications involving the heart, brain, kidney and lungs.

But over the same time period, health issues linked to metabolic function and the GI system increased, Al-Aly noted.

“People tend to think of SARS-CoV-2 as a homogeneous virus,” he said. “But each variant has its own fingerprint. The original virus hit the respiratory system hard. Omicron targeted metabolic and GI issues. It’s important because while the risk of long COVID is quantitatively lower, a person can be at a higher risk of developing an illness based on the part of the body that the COVID variant targets.”

The research was funded by the U.S. Department of Veterans Affairs.

More information

Find out more about Long COVID at the U.S. Centers for Disease Control and Prevention.

SOURCE: Washington University, news release, July 17, 2024

Source: HealthDay

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