The risk of developing long-term COVID-19 — persistent, sometimes severe symptoms that persist long after a coronavirus infection — has declined since the start of the pandemic, a new study finds, with the decline particularly evident among vaccinated people.
But that decline doesn’t mean the risk of developing long-term COVID has gone away. And given the surge in new infections, especially in times like these when data suggests transmission is high, even a lower prevalence rate means many Americans are at risk of developing symptoms that can last months or years after their initial infection clears.
“We have people in our clinic who have long COVID, and they are significantly affected, and some of them are profoundly disabled,” said Dr. Ziyad Al-Aly, chief of research and development at Veterans Affairs St. Louis Health Care System in Missouri.
The study, published Wednesday in the New England Journal of Medicine, found that 10.4% of people infected early in the pandemic suffered long-term COVID symptoms a year after their acute infection.
But during the Omicron era, which began in mid-December 2021 when this variant became the dominant version of the coronavirus circulating around the world, 3.5% of vaccinated people suffered long COVID a year after their infection, as did 7.8% of unvaccinated people.
“This is good news,” said Al-Aly, a co-author of the study. “Long COVID is on the decline. It’s on the decline and has been declining over the course of the pandemic.”
But it remains concerning that COVID rates will remain so high in the long term, Al-Aly said, especially since COVID is “still affecting millions of people.”
“Three point five percent is not zero,” Al-Aly said. “That’s still three to four people out of 100 who have a disease that could be, in some cases, devastating.”
The study drew on medical records held by the U.S. Department of Veterans Affairs, which had data on more than 441,000 veterans who were infected with the coronavirus between March 1, 2020, and January 31, 2022, and followed for a year after their infection to determine whether they had long COVID. Other co-authors are Yan Xie and Taeyoung Choi, who are also affiliated with the VA St. Louis Health Care System.
Any time someone is infected with the coronavirus, they are at risk of developing long COVID, an umbrella term used to describe a wide range of severe symptoms that can lead to chronic disability, according to the U.S. Centers for Disease Control and Prevention (CDC). Some people have had long COVID continuously since they were infected early in the pandemic, while others have seen their symptoms clear up within months.
Symptoms of long COVID include fatigue that disrupts daily life, brain fog, and post-exertional malaise, in which symptoms worsen with physical or mental exertion. Long COVID can also cause a fast or pounding heartbeat, dizziness when you stand up, depression, and anxiety.
Millions of American adults and children have suffered or are still suffering from long COVID.
There are several potential reasons why long COVID is rarer than it once was.
First, the coronavirus — officially known as SARS-CoV-2 — has changed significantly since it was first identified in December 2019.
“We always call it COVID, but the truth is, COVID has really changed shape on us, like, multiple times,” Al-Aly said.
This would explain why “the risk has actually decreased even in unvaccinated people,” Al-Aly said. “So even without being affected by the vaccines, the virus itself has attenuated over time.”
But as the study found, getting vaccinated further reduces the risk of developing long COVID.
“Vaccines do two things: First, they reduce the severity of the infection,” Al-Aly said.
Second, “they actually help your immune system get rid of the virus faster,” Al-Aly said. “They boost the immune system’s ability to clear the virus … and so there’s less virus that can wreak havoc” on organs and body systems.
According to Al-Aly, one of the leading theories about the root cause of long Covid is that the coronavirus lingers in the body long after an acute infection has ended. So if the vaccine helps the immune system get rid of the virus more quickly, it could reduce the risk of developing the syndrome.
“We know that vaccine immunity wanes over time,” Al-Aly said. “It’s absolutely important that you’re up to date on your vaccinations.”
The severity of long COVID varies from person to person. Some people may experience mild cognitive dysfunction or fatigue but can still perform daily tasks like taking their kids to school or walking the dog. Others may experience “fatigue that is so debilitating that it’s profoundly incapacitating, they can’t get out of bed… they literally can’t perform their activities of daily living,” Al-Aly said.
According to the CDC, long COVID can emerge, persist, resolve, and reappear over a period of weeks or months.
Other data suggest that the incidence of long COVID has declined since the start of the pandemic. According to survey data, the prevalence of long COVID among U.S. adults was 7.5% in early June 2022, but had fallen to about 6% by early January 2023, according to a report released last summer by the CDC. Since then, the “prevalence has remained unchanged” through mid-June 2023, shortly before that report was released.
About 1 in 4 adults who reported having long COVID in the survey reported having significant limitations in their usual activities — highlighting “the importance of COVID prevention, including staying up-to-date with recommended COVID-19 vaccination,” the report said.
COVID and long COVID remain a bigger public health threat than the flu. People with the flu sometimes have long-term complications, Al-Aly said, “but there are certainly a lot more cases of COVID than there are cases of the flu. So it’s much more likely, in terms of probability, that you’re going to get COVID than you are getting the flu.”
According to Al-Aly, even at this point, the number of COVID deaths and hospitalizations is higher than the number of flu cases. The CDC estimates that there have been at least 25,000 flu deaths nationwide since the beginning of October, compared to at least 46,000 COVID-19 deaths during the same period. Updated death estimates for the past flu season will be available this fall.
Besides vaccination, other ways to avoid long COVID include getting tested when you’re sick to see if you have COVID. A confirmed diagnosis can help high-risk people get a prescription for Paxlovid, antiviral pills that can help reduce the severity of infections and potentially reduce the risk of long COVID, Al-Aly said.
Other measures include wearing a mask in high-risk situations. Al-Aly said he wears an N95 mask on airplanes and uses masks strategically in high-risk environments. He’s also more vigilant about mask-wearing in the event of a COVID surge, as is currently happening nationwide. And eating at outdoor restaurants remains less risky than dining indoors.