Tag: COVID-19

It’s fall, which means it’s time to get updated on the winter season shots. That includes vaccines for flu, RSV (for babies and the elderly) and, for anyone six months or older, COVID-19.

While the new mRNA vaccines from Moderna and Pfizer-BioNTech have dominated the COVID-19 vaccine story, there is another type of shot that uses a more traditional vaccine-making technology, used by Novavax. The vaccine is generating interest among some people online who prefer the more tried and true approach behind the company’s shot, so here’s what you need to know.

How is Novavax’s vaccine different from mRNA vaccines?

Novavax uses a protein-based vaccine strategy, which means people getting the vaccine receive a protein made by the virus that their body’s immune systems then see as foreign and mount responses against. mRNA vaccines, by contrast, include snippets of mRNA genetic material from the COVID-19 virus’ spike protein.

Novavax makes its vaccine by first inserting the gene for a SARS-CoV-2 viral protein into an insect virus, then using this loaded virus to infect an armyworm, or larva, of a moth that infects cabbages. Using the larva, the virus then produces more copies of itself, and by default, more copies of the SARS-CoV-2 protein as well, and it is this COVID-19 protein that is then used in the vaccine.

Bob Walker, chief medical officer at Novavax, says this method does a good job of mimicking the way the SARS-CoV-2 virus naturally infects the body, which could theoretically lead to some benefits in terms of the immune response the vaccine generates, although the company and others are still conducting deeper studies to find out whether that’s the case. “The construct resembles the virus in terms of how the [body’s] immune cells might see it—the full length of the spike protein that represents the natural configuration of the viral protein,” he says. “And that has certain potential advantages.”

The protein is coupled with what vaccine makers call an adjuvant, or additional compound that further activates the immune system to enhance the body’s response to the virus. “One major advantage of the adjuvant is that it works not only on the antibody side in terms of the immune response, but it also activates the T cells,” says Walker. “And T cells have many functions in the body—one is to fight viruses, and the other is to help antibody-producing cells to make more antibodies.”

Is Novavax’s vaccine approved by the U.S. Food and Drug Administration (FDA)?

Novavax’s COVID-19 vaccine is not approved by the FDA yet, but it is available in the U.S. under emergency use authorization, which the FDA issued to the company in July 2022, and allows companies to make and distribute a product during a public health emergency while the FDA continues to review a broader set of data concerning its safety and efficacy. Novavax’s vaccine is safe and effective, but the agency is reviewing more robust and longer term data. Novavax has filed for full approval of its COVID-19 vaccine and expects a decision from the FDA by April 2025.

Both Pfizer-BioNTech and Moderna have received approval for adults for their COVID-19 vaccines, in 2021 and 2022, respectively, after first receiving emergency use authorization in 2020. Their shorter timeline was due mainly to the fact that the mRNA technology streamlines the development and manufacturing time for the shots. Because Novavax’s vaccine-making process requires more time, and different types of testing, Walker says it’s taken longer to complete the regulatory requirements for approval. But “with each successive season, we are getting faster and more efficient in manufacturing our vaccines, and we think we will be able to shorten that difference in time,” he says. “But I don’t know that we will ever surpass mRNA [technology’s timeline] just because of the technological and testing requirement differences.”

Which vaccine provides better protection against COVID-19?

Studies conducted by academic researchers over the past few years consistently show that there are few major differences between the mRNA and Novavax vaccines in terms of the immune responses they generate. Researchers generally measure this by looking at levels of neutralizing antibodies that the body makes against SARS-CoV-2, which were comparable across all three manufacturers’ vaccines. Some studies have also looked at T cell responses which also appear to be similar among the three shots so far.

Is one vaccine better at protecting against the new COVID-19 variants?

Over the summer, the FDA recommended that vaccine makers target the KP.2 strain of SARS-CoV-2 for the upcoming fall and winter season, and studies from Moderna, PfizerBioNTech, and Novavax show that each of the company’s updated vaccines provide strong protection against this strain as well as some of the even newer ones that have emerged in recent months. That’s because all of the variants remain related and are part of the Omicron group.

I’ve heard Novavax vaccine has fewer side effects. Is that true?

There haven’t been enough rigorous side-by-side comparisons of side effects and adverse events between the mRNA vaccines and the Novavax shot; instead each manufacturer has provided the FDA with reports of side effects that each has seen in its respective studies. But it appears that so far, people receiving the Novavax vaccine may be reporting fewer events such as fever, muscle aches, and headaches compared to those receiving either mRNA vaccine. All COVID-19 vaccines from the three manufacturers have been linked to an increased risk of inflammation of heart muscle, or pericarditis or myocarditis—most of the studies involving the risk with Novavax’s vaccines have come from outside of the U.S.

Which vaccine should I get this year?

“The best vaccine is the one that is in your arm,” says Walker. “We are in the fortunate position that we have multiple options, and are not relying on one technology to achieve very high levels of protection and safety. The FDA has determined that all of these vaccines are safe and effective.”

Not long ago, Mark Chiverton, a 33-year-old in the U.K., noticed he was making a lot of silly mistakes. He’d mix up words when writing emails, or blank on a basic term while talking to his wife. None of these slip-ups were all that concerning on their own—but they were happening frequently enough that Chiverton worried he was, to put it bluntly, “getting dumber.”

“At first I thought, ‘Maybe it’s just general aging, or maybe I bashed my head and didn’t realize it,’” he says. But eventually, a thought occurred to him: could COVID-19 be the reason for his mental slips? Chiverton thinks he caught the virus in early 2020, before tests were widely available, and he knows for sure he had it in 2022. Though he has no lingering physical effects from those infections (and has periods of time when his brain cramps get better), he sometimes wonders whether those mental slips are mild signs of Long COVID, the name for chronic symptoms following an infection.

He’s not alone in experiencing these problems—and he may not be wrong that COVID-19 is to blame. In the U.S. alone, about a million more working-age adults reported having serious difficulty remembering, concentrating, or making decisions in 2023 compared to before the pandemic, according to a New York Times analysis of Census Bureau data.

Every mental mistake isn’t cause for concern, says Andrew Petkus, an associate professor of clinical neurology at the University of Southern California’s Keck School of Medicine. Blunders like forgetting why you walked into a room or spacing out on an appointment can be totally normal parts of being busy, distracted, often under-rested humans. Even though you likely did those things before and brushed them off as nothing, they may seem more significant in the wake of a life-altering event like the pandemic. “If we didn’t have COVID, you might have still forgotten,” Petkus says.

Still, it’s not outlandish to think the pandemic has had an effect on our minds, says Jonas Vibell, a cognitive and behavioral neuroscientist at the University of Hawaii at Manoa. Vibell is currently trying to measure post-COVID inflammation and neuronal damage in the brains of people who report symptoms like brain fog, sluggishness, or reduced energy. When he began publicizing the study, he says, “I got so many emails from lots of people saying the same thing”: that they’d never fully bounced back after the pandemic.

But why? It’s probably a mix of things, Vibell says. The SARS-CoV-2 virus can affect the brain directly, as many studies have now shown. But the pandemic may have also affected cognition in less-obvious ways. Months or years spent at home, living most of life through screens, may have left a lingering mark. Even though society is now mostly back to normal, the trauma of living through a terrifying, unprecedented health crisis can be hard to shake.

Your brain on SARS-CoV-2

It’s clear by now that SARS-CoV-2 is not just a respiratory virus, but also one that can affect organs throughout the body—including the brain. Researchers are still learning about why that is, but leading hypotheses suggest that SARS-CoV-2 may cause persistent inflammation in the brain, damage to blood vessels in the brain, immune dysfunction so extreme it affects the brain, or perhaps a combination of all the above. Studies have even found that people’s brains can shrink after having COVID-19, a change potentially associated with cognitive issues.

COVID-19 has been linked to serious cognitive problems, including dementia and suicidal thinking. And brain fog, a common symptom of Long COVID, can be so profound that people are unable to live the lives and work the jobs they once did. But COVID-19 also seems able to affect the brain in subtler ways. A 2024 study in the New England Journal of Medicine compared the cognitive performance of people who’d fully recovered from COVID-19 with that of a similar group of people who’d never had the virus. The COVID-19 group did worse, equivalent to a deficit of about three IQ points.

That’s not a dramatic difference. Our cognitive abilities naturally fluctuate a little from day to day—and in a July interview with TIME, study co-author Adam Hampshire, a professor of cognitive and computational neuroscience at King’s College London, said a three-point IQ difference is “well within” the range of that normal fluctuation, so small that some people might not even notice it.

But could such a drop be enough to lead to, say, extra typos and absentmindedness? Maybe. In Hampshire’s study, people who’d had COVID-19 consistently performed worse on cognitive tests than people who hadn’t.

If the brain suffers “mild but ubiquitous” changes after an infection, Vibell says, those effects could feasibly “impact the brain, behavior, and social behavior in so many subtle, but maybe [cumulatively] quite bad, ways.”

Beyond the virus

Even for the lucky few who have never been infected, living through a pandemic can impact the brain.

For a recent study in PNAS, researchers conducted pairs of MRI brain scans on a small group of U.S. adolescents: one in 2018 and one in either 2021 or 2022. Over those years, they observed a notable thinning in parts of the kids’ (and especially girls’) brains, including those that control social cognition tasks like processing facial expressions and emotions. Although the researchers did not analyze the effects of SARS-CoV-2 infections, they concluded that the stress of living through pandemic lockdowns was likely to blame for the change, which they likened to an extra four years of brain aging for girls and an extra year for boys.

Stress and trauma have well-documented effects on the brain. Plenty of studies show that people who experience trauma tend to be at greater risk for cognitive decline as they age. Stress can also impair someone’s ability to think clearly, reason, and remember, studies suggest.

“COVID was a generational traumatic event,” says USC’s Petkus. “Everybody was exposed to it.” It’s feasible, then, that the population at large is suffering some of these side effects from trauma and stress.

Even beyond the mental toll of living through a scary and unsettling time, many people had to abandon habits that are good for the brain—things like socializing, staying physically and cognitively active, and seeking out novel experiences—when they were stuck at home early on, Petkus says. It’s too soon to say whether that dramatic but short-lived period will have long-lasting effects—but four years after the virus emerged, some things are still not as they were.

For example, student test scores are recovering but have still not bounced back to pre-pandemic levels; declines have been particularly dramatic in low-income school districts as well as those that had remote learning in place for a long time, says Sean Reardon, a professor at Stanford University’s Graduate School of Education and one of the leaders of the Education Recovery Scorecard, a research project focused on pandemic learning loss. The long recovery process probably speaks to a combination of things, Reardon says: not only did kids miss in-person school for a while, they also experienced seismic disruptions in their lives, endured a period of significant stress and anxiety, and are now being asked to learn new material in school while also making up for pandemic-related learning gaps.

“Falling behind on your math skills or your reading skills is not really about a change in your intelligence,” Reardon says. “It’s a change in your skills, how much you’ve had the opportunity to learn.” 

It’s hard to say whether the same trends appear among adults, because grownups aren’t taking standardized tests every year at work. Adults were certainly exposed to the same mix of stress, trauma, boredom, and isolation as kids—but Reardon says his hunch is that adults may have an easier time rebounding, since they’ve already developed the skills they lean on to perform complex tasks.

Returning to normal

“There might have been a shock for a couple years, but things are getting back to normal,” Petkus agrees. 

Those who feel like their minds melted a little during the pandemic can likely benefit from adopting or resuming the kinds of brain-boosting habits that fell by the wayside during Netflix-fueled lockdowns, like social interaction and mental and physical exercise, Petkus says. Even the effects of stress and trauma can often be counterbalanced with social support and healthy coping strategies, he says. People who recover well from hard events sometimes even experience what’s known as post-traumatic growth, a blossoming of their mental and emotional health after a difficult period.

It’s harder to say whether brain changes that result directly from SARS-CoV-2 infections are reversible, as researchers are still studying that question. But there are some positive signs. Some of the potential causes of chronic brain fog—like persistent inflammation or damage to blood vessels—are theoretically reversible with the right treatments.

Even in Hampshire’s study on post-COVID IQ differences, there was cause for optimism. Hampshire’s team found that people with Long COVID symptoms were, on average, about six IQ points beneath people who’d never had COVID-19. But those whose Long COVID symptoms resolved over time also saw their cognitive scores improve.

That finding is “quite positive,” he said. “There could be some hope for people who are struggling.”

These days, many people use at-home COVID-19 tests when they feel ill, rather than going out to get tested by a professional. (That’s when they bother to test at all.) But for all their convenience, the antigen tests commonly used at home have never been as accurate as PCR tests done in a lab—and the continued mutation of the virus raises additional concerns about their performance.

Rapid COVID-19 tests have never been perfect. How are they holding up as new variants emerge?

The U.S. Food and Drug Administration (FDA) continues to monitor the efficacy of the diagnostics it regulates—and as of August 2023, the FDA said none of the antigen tests on the market were expected to have reduced performance against Omicron or its subvariants. (All of the variants that have emerged since late 2021, including recent ones like KP.3.1.1, are relatives of the original Omicron strain.)

The FDA has also collaborated with a U.S. National Institutes of Health task force set up to monitor how variants affect tests. In 2022, well into Omicron’s dominant era, that team concluded that DIY diagnostics continued to work well. Task force member Richard Creager wrote in an email to TIME that the tests still seem able to catch the Omicron spinoffs that are circulating now. “The rapid tests are having no issue detecting the variants,” he wrote, noting that the protein that antigen tests look for has remained fairly stable as the virus changes.

Read More: Does Text Therapy Really Work?

Even if tests have remained constant, our immune systems haven’t. Early in the pandemic, an infected person’s “viral load”—the amount of virus in their system—tended to peak around the time their symptoms began. So if someone self-tested on the first or second day they felt sick, they likely had enough virus in their body for a rapid test to detect it.

Now that most everyone has prior immunity from multiple vaccines or infections, the timeline seems to be extended. Viral load now tends to peak around day four or five of symptoms, according to a study published in early 2024. That’s likely because the immune system is primed for action by its previous encounters with the virus, so it responds faster, even before lots of virus has built up in the body. A quicker immune response may mean a faster onset of symptoms.

“If your body has seen the virus before, you’re going to react to it and have an immune response more quickly,” explains study co-author Dr. Nira Pollock, co-director of the Infectious Diseases Diagnostic Laboratory at Boston Children’s Hospital. “That immune response can show up as symptoms.”

From an immune perspective, that’s a good thing. But it can complicate testing, because it means someone may not test positive for COVID-19 until they’ve already been feeling sick for days. In their recent study, Pollock and her co-authors estimated that a COVID-19 antigen test is somewhere between 30% and 60% accurate at detecting an infection on someone’s first day of symptoms, but up to 93% accurate on day four.

Based on such findings, Pollock and other researchers cautioned in a recent review article that people who are symptomatic shouldn’t assume they’re COVID-free based on a single negative antigen test result. Although it’s a hard sell for people who no longer take precautions, the ideal scenario is for someone to stay isolated—or at least wear a mask when around other people—and test again around day four of symptoms.

Read More: The 1 Heart-Health Habit You Should Start When You’re Young

“The instructions for these tests are to do serial testing,” Pollock says. “If you’re symptomatic, you should test early. But if you’re negative, you need to repeat it, because the amount of virus in your nose may not be high enough yet to detect.”

One other factor to consider: tests don’t last forever. Many people stockpiled tests when they were previously available for free through government programs and insurance, and those kits may have since expired. (You’ll soon be able to order four more free tests through the government.) The FDA’s website provides up-to-date guidance on determining how long your kits last.

Expired tests can still work, says Dr. Zishan Siddiqui, an assistant professor at the Johns Hopkins University School of Medicine. He co-authored a 2023 study on Abbott’s popular BinaxNOW tests, which found no major accuracy differences between unexpired tests and those that were five months past expiration. (Siddiqui’s other research suggests unexpired BinaxNOW tests accurately detect COVID-19 cases more than 80% of the time.)

But, although Siddiqui says he isn’t too worried about using expired tests, it’s good to remember that their performance can suffer if they’re long past their recommended use dates. If the control line on your test strip doesn’t show up or looks distorted, that’s a good indication that it’s too old to use, he says. Even in Siddiqui’s study, which found that expired tests still work, the lines on the old tests showed up more faintly than on fresh tests, making them harder to read.

Whether your tests are old or brand new, it’s good to use some healthy skepticism when interpreting their results. “I trust these tests,” even as the virus evolves, Siddiqui says—but a single result doesn’t always tell the whole story. If you have COVID-like symptoms but test negative, it’s best to be cautious and retest in a few days.

Every medical intervention comes with both benefits and risks. For vaccinations, the benefits greatly outweigh any potential hazards in most people.

The new COVID-19 vaccines based on mRNA technology are no exception. But one risk associated with them—myocarditis, especially for young men—has raised concerns among the public.

A new study published in JAMA has found that the risk associated with getting myocarditis—which is inflammation of the heart muscle, often triggered by the immune system as it responds to an infection—shortly after getting the COVID-19 vaccine is lower than the risk that can come from getting the disease.

Read More: The Best Way to Treat Insomnia

Researchers led by Dr. Mahmoud Zureik, professor of epidemiology and public health at the University of Versailles, studied people ages 12 to 49 who had been hospitalized with myocarditis in France from Dec. 2020 to June 2022, when mass vaccination campaigns were taking place. They sorted people into three groups: people who developed myocarditis and were hospitalized within seven days of receiving an mRNA shot, those who were admitted to the hospital within 30 days of getting COVID-19 but had not had an mRNA vaccine in the prior seven days, or people who had myocarditis that was due to other causes. Everyone was followed for 18 months.

In that time period, people with vaccine-related myocarditis were half as likely to be readmitted to the hospital for myocarditis or heart-related events compared to those with infection-related myocarditis or people with myocarditis due to other causes.

The findings indicate that the risk of myocarditis linked to the mRNA vaccines “is very, very low,” says Zureik. And it’s important to remember that the risk of COVID-19 to the heart “is not limited to myocarditis. There are other cardiovascular risks as well.”

Read More: Long COVID Looks Different in Kids

The results are timely, as COVID-19 cases and emergency room visits continue to climb in the U.S.. The increases are due in part to new variants and waning immunity people have from their last vaccines, which targeted different versions of SARS-CoV-2. That’s why the U.S. Food and Drug Administration recently approved an updated version of the vaccine to recognize the currently circulating variants. But uptake of recent shots has been low.

The study did not delve into the reason why the vaccines are linked—however slightly—to myocarditis, or why the immune system’s response to the vaccine seems to be different than that generated by a COVID-19 infection. It’s possible that because people are aware of the potential myocarditis risk associated with the vaccine, people hospitalized for the condition after getting vaccinated could have milder cases, Zureik says.

More research is needed to better understand how the mRNA vaccines are interacting with the body’s immune system, but the findings provide some confidence that the shots do not seem to be associated with any substantially greater risk of heart inflammation, even months after immunization.

Chances are, at least one person you know—and probably many people you know—have caught COVID-19 this summer. Ever since the “FLiRT” variants emerged this spring, the U.S. has been hit with one new variant after another, leading to a seemingly never-ending wave of cases. The amount of virus in wastewater has steadily risen since May and levels are now “very high,” in part because there’s yet another new variant on the scene: KP.3.1.1.

KP.3.1.1 was to blame for more than a third of new COVID-19 cases in the U.S. during the two weeks ending Aug. 17, U.S. Centers for Disease Control and Prevention (CDC) data show. And that’s a lot of cases: about one in 34 people in the U.S. currently has COVID-19, independent data scientist and infectious-disease modeler Jay Weiland tells TIME. CDC data also show that lots of people are testing positive and that hospital visits and deaths related to COVID-19 are on the rise.

What will KP.3.1.1 do next? Here’s what to know.

What is KP.3.1.1?

Like other variants that have recently become widespread in the U.S., including KP.2 and KP.3, KP.3.1.1 descended from JN.1, the Omicron relative that caused this past winter’s surge. Weiland considers KP.3.1.1 a “sibling” of the original FLiRT strains, because they have the same “parent” variant but are slightly different in composition.

Read More: Should You Work Out if Your Muscles Are Sore?

KP.3.1.1 has some changes that have allowed it to take off, according to pre-publication research posted online in July. It seems to be more infectious than KP.3 and better at evading antibodies generated both by previous infections and the COVID-19 vaccines distributed this past fall, the study says. A medication authorized by the U.S. Food and Drug Administration (FDA) to prevent COVID-19 illnesses among immunocompromised people also does not seem to work as well against KP.3.1.1 compared to prior variants, according to another pre-publication study posted online in August.

Are we going to keep seeing lots of infections?

The silver lining of our COVID-filled summer is that many people have fresh immunity from recent cases. That means KP.3.1.1 doesn’t have as many vulnerable people to infect as it would have if it had become dominant a couple months ago, Weiland says.

Read More: What’s So Great About Cottage Cheese?

“I think we’re at the peak of this summer wave,” he says. KP.3.1.1’s ascent might prolong the surge a bit, but Weiland thinks it’s unlikely to lead to a major second spike given how much immunity there currently is in the population. 

The exception may be among kids who are returning to school while COVID-19 is still spreading widely. There may be a noticeable uptick in cases within that age group, Weiland says.

Will future vaccines work against KP.3.1.1?

On Aug. 22, the FDA greenlit a new COVID-19 vaccine for the 2024-2025 respiratory disease season, and it was designed to target KP.2. Since KP.2 is a close relative of KP.3.1.1, the new shot is likely to work fairly well against the currently circulating variant. These updated shots should be available to people of all ages in the coming weeks, according to the manufacturers, Pfizer-BioNTech and Moderna—good timing, with lots of virus still going around.

Novavax is also seeking regulatory approval of a shot meant to target JN.1, which would likely also provide some protection against its descendant KP.3.1.1.

Amid an ongoing surge, the U.S. Food and Drug Administration (FDA) has approved updated COVID-19 vaccines for the 2024-2025 respiratory disease season.

The new shots, made by Moderna and Pfizer-BioNTech, are largely the same as the original mRNA vaccines developed at the start of the pandemic—but they target KP.2, a different strain of the virus that has been causing many of the rising number of cases this summer. The FDA initially recommended in early June that vaccine makers target the JN.1 lineage—of which KP.2 is a part—but changing patterns in which variants are causing disease led the agency to update its advice in August, asking manufacturers to focus on KP.2.

Why are the new shots targeting this variant?

KP.3 variants currently account for nearly half of COVID-19 infections in the U.S., and KP.2 variants cause about 14.4% of cases, according to the U.S. Centers for Disease Control and Prevention. The new vaccines are targeting KP.2 because the virus continues to mutate more quickly than manufacturers can follow them with a perfectly matched vaccine—and that’s even with the mRNA technology, which allows scientists to produce vaccines against a new target in just six to eight weeks. Testing that shot, and scaling up manufacturing, takes a few more months.

The good news, however, is that all of the JN and KP variants are related and belong to a group known as FLiRT, an acronym that encompasses the mutations these variants developed. They all have different names because they each developed similar mutations independently. That means that a vaccine targeting one will likely still be effective against others in the group, although at varying levels. A Moderna spokesperson says its updated KP.2 vaccine generated stronger immune responses against JN.1 variants, including KP.2 and KP.3, compared to its previous XBB vaccine. A Pfizer spokesperson says its tests showed similarly stronger immune responses with its updated KP.2 vaccine against JN.1 offshoots, including KP.3 and LB.1, compared to its XBB shot.

Read More: Should You Work Out If Your Muscles Are Sore?

The bad news is that the FLiRT mutations make it difficult for antibodies that the body generates—either from exposure to the vaccine through an infection or a vaccine—to neutralize the virus. But these changes also make it harder for the virus to attach to and infect cells. But overall, the ability of FLiRT variants to evade antibody defenses have allowed them to spread more quickly among people, although they don’t seem to cause more serious disease in most people.

Who should get the new shot?

The FDA approved both vaccines from Moderna and Pfizer-BioNTech for people 12 years and older. For children ages six months to 11 years, the agency issued an emergency use authorization, which allows manufacturers to distribute the vaccine while additional data on safety and side effects in that age group continue to be collected. People over age 65 continue to be at the highest risk of being hospitalized for complications related to COVID-19—nearly 18 times the rate of younger people, according to the CDC.

When can I get vaccinated?

Both companies say they expect doses of their vaccines to be available at pharmacies and doctors’ offices in the coming weeks. Walgreens says its first appointments for COVID-19 vaccines will be on September 6. In order to help more doctor’s offices stock the vaccines and encourage greater uptake, a Pfizer spokesperson says its vaccine will have a longer shelf life than its past vaccines and come in smaller, pre-filled syringe packs of 10 to reduce waste.

Adults with Long COVID can experience a slew of different symptoms, but some are more common than others. Intense fatigue, crashes after mental or physical effort, brain fog, shortness of breath or coughing that won’t go away, and the loss of smell or taste are some of Long COVID’s hallmarks.

For kids, however, it’s another story. New research, published Aug. 21 in JAMA, finds that Long COVID symptoms can look different among children compared to adults—and even among kids of different age groups.

“Most of what we know about Long COVID, we know from studies of adults,” says Dr. Rachel Gross, an associate professor of pediatrics at the NYU Grossman School of Medicine and co-lead author of the new study, which is part of the U.S. National Institutes of Health’s RECOVER research initiative. “This is one of the largest and first studies to try to characterize the prolonged symptoms that are experienced by children and to try to understand how they may differ between different age groups.”

To do so, Gross and her colleagues surveyed the caregivers of more than 5,000 U.S. children—some who had previously had COVID-19 and others who hadn’t—about lingering health issues their kids developed during the pandemic. They then sorted through the caregivers’ answers, along with data about the kids’ COVID-19 histories, to figure out which symptoms were most closely linked to prior infections, and thus seemed to be especially good indicators of Long COVID in children.

Among children ages 6 to 11, the researchers identified 10 symptoms strongly linked to Long COVID: 

Read More: What to Do If Your High Cholesterol Is Genetic

Among adolescents ages 12 to 17, eight key symptoms emerged:

Identifying these symptoms alone isn’t enough to officially diagnose Long COVID, at least not without additional research to confirm the findings. But for the purposes of the study, the researchers used them as a guide for estimating which kids likely had Long COVID. They estimated that 20% of the previously infected younger children and 14% of the previously infected adolescents met that threshold. Kids infected before the Omicron wave were especially likely to fall into the Long COVID category.

Those numbers are higher than some previous estimates—for example, a recent U.S. Centers for Disease Control and Prevention report concluded that only about 1% of U.S. kids had had Long COVID as of 2022. But other studies have come to similar conclusions, estimating that somewhere between 10% and 20% of kids who catch COVID-19 will develop long-term complications.

Read More: The Best Way to Treat Insomnia

With so many outstanding questions about how many kids and which ones develop Long COVID, it’s important for clinicians to know the symptoms to look for, Gross says. There’s a “misperception” that “if children have Long COVID, it will look like Long COVID in adults,” she says. But that’s not necessarily true. Gross’ study and others suggest kids can experience a wide range of complications after a case of COVID-19, reporting everything from sleep disorders and behavioral issues to nasal congestion.

Some Long COVID symptoms, like fatigue and cognitive issues, do seem to be shared across age groups. But some of the pediatric symptoms identified in the new study—like phobias and rashes—are not typically associated with adult Long COVID, and thus might be missed or misattributed if clinicians looked only for common adult symptoms.

As of now, even a correct Long COVID diagnosis doesn’t mean a child will get adequate treatment. Researchers are looking for therapies, but there is not yet any test or treatment specifically approved and shown to be effective against Long COVID.

The results of the new study should reframe how parents think about the risks the virus poses to their children, Gross says. It’s true that kids are less likely than adults to get severely ill or die if they catch COVID-19. But long-term complications are possible for people of any age—even if they don’t look the same across life stages.