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Possible risk of autism in children. Dormant cancer cells awakening. Accelerating aging of the brain.
Federal officials in May 2023 declared an end to the national covid pandemic. But more than two years later, a growing body of research continues to reveal information about the virus and its ability to cause harm long after initial infections resolve, even in some cases when symptoms were mild.
The discoveries raise fresh concerns about the Trump administration’s covid policies, researchers say. While some studies show covid vaccines offer protective benefits against longer-term health effects, the Department of Health and Human Services has drastically limited recommendations about who should get the shot. The administration also halted Biden-era contracts aimed at developing more protective covid vaccines.
The federal government is curtailing such efforts just as researchers call for more funding and, in some cases, long-term monitoring of people previously infected.
“People forget, but the legacy of covid is going to be long, and we are going to be learning about the chronic effects of the virus for some time to come,” said Michael Osterholm, an epidemiologist who directs the University of Minnesota’s Center for Infectious Disease Research and Policy.
The Trump administration said that the covid vaccine remains available and that individuals are encouraged to talk with their health providers about what is best for them. The covid vaccine and others on the schedule of the Centers for Disease Control and Prevention remain covered by insurance so that individuals don’t need to pay out-of-pocket, officials said.
“Updating CDC guidance and expanding shared clinical decision-making restores informed consent, centers parents and clinicians, and discourages ‘one size fits all’ policies,” said HHS spokesperson Emily Hilliard.
Although covid has become less deadly, because of population immunization and mutations making the virus less severe, researchers say the politicization around the infection is obscuring what science is increasingly confirming: covid’s potential to cause unexpected, possibly chronic health issues. That in turn, these scientists say, drives the need for more, rather than less, research, because over the long term, covid could have significant economic and societal implications, such as higher health care costs and more demands on social programs and caregivers.
The annual average burden of the disease’s long-term health effects is estimated at $1 trillion globally and $9,000 per patient in the U.S., according to a report published in November in the journal NPJ Primary Care Respiratory Medicine. In this country, the annual lost earnings are estimated to be about $170 billion.
One study estimates that the flu resulted in $16 billion in direct health costs and $13 billion in productivity losses in the 2023-2024 season, according to a Dec. 30 report in medRxiv, an online platform that publishes work not yet certified by peer review.
Covid’s Growing Reach
Much has been learned about covid since the virus emerged in 2019, unleashing a pandemic that the World Health Organization reports has killed more than 7 million people. By the spring of 2020, the term “long covid” had been coined to describe chronic health problems that can persist post-infection.
More recent studies show that infection by the virus that causes covid, SARS-CoV-2, can result in heightened health risks months to more than a year later.
For example, researchers following children born to mothers who contracted the virus while pregnant have discovered they may have an increased risk for autism, delayed speech and motor development, or other neurodevelopmental challenges.
Another study found babies exposed to covid in utero experienced accelerated weight gain in their first year, a possible harbinger of metabolic issues that could later carry an increased risk for cardiovascular disease.
These studies suggest avoiding severe covid in pregnancy may reduce risk not just during pregnancy but for future generations. That may be another good reason to get vaccinated when pregnant.
“There are other body symptoms apart from the developing fetal brain that also may be impacted,” said Andrea Edlow, an associate professor of obstetrics, gynecology, and reproductive biology at Harvard Medical School who was involved in both studies. “We definitely need more research.”
Epidemiologists point to some specific, emerging challenges.
A U.K. study in the New England Journal of Medicine found people who fully recovered from mild covid infections experienced a cognitive deficit equal to a three-point drop in IQ. Among the more than 100,000 participants, deficits were greater in people who had persistent symptoms and reached the equivalent of a nine-point IQ drop for individuals admitted to intensive care.
Ziyad Al-Aly, a clinical epidemiologist who has studied longer-term health effects from covid, did the math. He estimated covid may have increased the number of adults in the U.S. with an IQ of less than 70 from 4.7 million to 7.5 million — a jump of 2.8 million adults dealing with “a level of cognitive impairment that requires significant societal support,” he wrote.
“People get covid-19, some people do fine and bounce back, but there are people who start experiencing problems with memory, cognition, and fuzzy brain,” he said. “Even people with mild symptoms. They might not even be aware.”
Diane Yormark, 67, of Boca Raton, Florida, can relate. She got covid in 2022 and 2023. The second infection left her with brain fog and fatigue.
“I felt like if you had a little bit too much wine the night before and you’re out of it,” said Yormark, a retired copywriter, who said the worst of her symptoms lasted for about three months after the infection. “Some of the fog has lifted. But do I feel like myself? Not like I was.”
Data from more than a dozen studies suggests covid vaccines can help reduce risk of severe infection as well as longer-lasting health effects, although researchers say more study is needed.
But vaccination rates remain low in the U.S., with only about 17% of the adult population reporting that they got the updated 2025-2026 shot as of Jan. 16, based on CDC data.
Trump administration officials led by Health and Human Services Secretary Robert F. Kennedy Jr. have reduced access to covid vaccines despite the lack of any new, substantiated evidence of harm. Though the shots were a hallmark achievement of the first Trump administration, which led the effort for their development, Kennedy has said without evidence that they are “the deadliest vaccine ever made.”
In May he said on X that the CDC would stop recommending covid shots for healthy children and pregnant women, citing a lack of clinical data. The Food and Drug Administration has since issued new guidelines limiting the vaccine to people 65 or older and individuals 6 months or older with at least one risk factor, though many states continue to make them more widely available.
The Trump administration also halted almost $500 million in funding for mRNA-based vaccines. Administration officials and a number of Republicans question the safety of the Nobel Prize-winning technology — heralded for the potential to treat many diseases beyond covid — even though clinical trials with tens of thousands of volunteers were performed before the covid mRNA vaccines were made available to the public.
And numerous studies, including new research in 2025, show covid vaccine benefits include a reduction in the severity of disease, although the protective effects wane over time.
Following the Findings
Researchers say more and broader support is important because much remains unknown about covid and its impact on the body.
The growing awareness that, even in mild covid cases, the possibility exists for longer-term, often undetected organ damage also warrants more examination, researchers say. A study published this month in eBioMedicine found people with neurocognitive issues such as changes in smell or headaches after infection had significant levels of a protein linked to Alzheimer’s in their blood plasma. EBioMedicine is a peer-reviewed, open-access journal published by The Lancet.
In the brain, the virus leads to an immune response that triggers inflammation, can damage brain cells, and can even shrink brain volume, according to research on imaging studies that was published in March 2022 in the journal Nature.
An Australian study of advanced brain images found significant alterations even among people who had already recovered from mild infections — a possible explanation for cognitive deficits that may persist for years. Lead study author Kiran Thapaliya said the research suggests the virus “may leave a silent, lasting effect on brain health.”
Al-Alay agreed.
“We don’t know what will happen to people 10 years down the road,” he said. “Inflammation of the brain is not a good thing. It’s absolutely not a good thing.”
That inflammatory response has also been linked to blood clots, arrhythmias, and higher risk of cardiovascular issues, even following a mild infection.
A University of Southern California study published in October 2024 in the journal Arteriosclerosis, Thrombosis, and Vascular Biology found the risk for a major cardiac event remains elevated nearly three years after covid infection. The findings held even for people who were not hospitalized.
“We were surprised to see the effects that far out” regardless of individual heart disease history, said James R. Hilser, the study’s lead author and a postdoctoral fellow at the UCLA David Geffen School of Medicine.
Covid can also reactivate cancer cells and trigger a relapse, according to research published in July in the journal Nature. Researchers found that the chance of dying from cancer among cancer survivors was higher among people who’d had covid, especially in the year after being infected. There was nearly a twofold increase in cancer mortality in those who tested positive compared with those who tested negative.
The potential of the covid virus to affect future generations is yielding new findings as well. Australian researchers looked at male mice and found that those who had been infected with and then recovered from covid experienced changes to their sperm that altered their offspring’s behavior, causing them to exhibit more anxiety.
Meanwhile, many people are now living — and struggling — with the virus’ after-effects.
Dee Farrand, 57, of Marana, Arizona, could once run five miles and was excelling at her job in sales. She recovered from a covid infection in May 2021.
Two months later, her heart began to beat irregularly. Farrand underwent a battery of tests at a hospital. Ultimately, the condition became so severe she had to go on supplemental oxygen for two years.
Her cognitive abilities declined so severely she couldn’t read, because she’d forget the first sentence after reading the second. She also had to leave herself reminders that she is allergic to shrimp or that she likes avocados. She said she lost her job and returned to her previous occupation as a social worker.
“I was the person who is like the Energizer bunny and all of a sudden I’d get so tired getting dressed that I had to go back to bed,” Farrand said.
While she is better, covid has left a mark. She said she’s not yet able to run the five miles she used to do without any problems.