As many as one in four seniors and one in five adults under 65 experienced "long COVID" or "post-COVID" symptoms after surviving a coronavirus infection, a new study from the Centers for Disease Control and Prevention reported Tuesday.
The study — published in the CDC's Morbidity and Mortality Weekly Report — is the latest to try and quantify how many of the millions of Americans who have now tested positive for the virus are facing long-term issues caused by their infection.
By comparing electronic health records in a large national database of patients, the study's authors found 38.2% of COVID-19 survivors "experienced at least one incident condition" — a list that includes heart, lung, kidney and gastrointestinal problems, pain, fatigue, loss of smell or taste, mental health issues, and more — in the months after their infection. By contrast, just 16% of other people were diagnosed with such conditions.
"As the cumulative number of persons ever having been infected with SARS-CoV-2 increases, the number of survivors suffering post-COVID conditions is also likely to increase," the study's authors wrote.
The study only looked at data from March 2020 to November 2021, before the massive Omicron variant surge over the winter. Based on surveys of antibodies, the CDC estimates that the share of Americans who have survived the virus rose to nearly 60% over the winter, up from a third in December.
Among the 26 conditions examined by the study, the most common symptoms were "respiratory symptoms and musculoskeletal pain" in both seniors and other adults.
Among seniors aged 65 years and older, the researchers warned they were at "increased risk for neurological conditions" and other mental health issues ranging from mood disorders to substance abuse.
Another study also published this week, from scientists at Northwestern University, reported that many so-called "long haulers" were facing conditions like brain fog and numbness for more than a year after their initial infection.
The CDC study's authors also note there are some factors that might complicate their estimates.
For example, doctors may have been "more likely to document possible post-COVID conditions" among people who have survived the virus, leading to an overestimate of the risk of these symptoms.
On the other hand, the study's comparison to others without a prior infection was drawn from other patients who were "seeking care." That could lead to an underestimate of the true risk elevated by an infection, the study's authors said, given these others might actually be "sicker" than a true control group.
Previous studies have reached varying estimates of the share of survivors who face long COVID symptoms. Some of that may be the result of the wide range of ways scientists have defined post-COVID in their studies, looking at different time intervals since infection or different symptoms.
"You see numbers out there of like 30, 50 percent. I think that's clearly not quite right in terms of thinking about how many people are really disabled by this in a significant way," Dr. Ashish Jha, the White House's top COVID-19 official, told the "In the Bubble" podcast earlier this month.
"But that said, what that means, unfortunately, is other people minimize long COVID," Jha added.
The latest report is among several ongoing studies the CDC has backed with the aim of understanding the impact of post-COVID symptoms.
The CDC revamped its guidance on post-COVID earlier this month, adding conditions like "depression or anxiety" to the list of commonly reported symptoms. The agency also laid out a list of reasons some people might be at higher risk after surviving COVID-19, like those who have faced a more severe illness or who were unvaccinated.
However, the guidance notes that more research – including both from the CDC and elsewhere at the National Institutes of Health – still needs to be done into how to treat these post-COVID patients.
Advocates said recently that they are in talks with the Biden administration over long COVID plans to be released in August. The NIH has said it plans to launch studies this year into trialing potential drugs to treat post-COVID conditions.
"I think we need to start trying out new therapies. I am interested in questions like, does getting Paxlovid reduce your likelihood of long COVID. Because if you have a much shorter duration of viremia is that going to make a difference?" said Jha.