Estimates of the number of people in the US with lingering Covid-19 symptoms vary widely, but a new survey from the National Center for Health Statistics says the condition may have affected as many as 962,000 children and 17.9 million adults.
In 2022, according to the agency, 1.3% of children and 6.9% of adults had ever had long Covid. However, only 0.5% of children and 3.4% of adults said they had long Covid at the time of the survey.
The estimates are consistent with some US Centers for Disease Control and Prevention surveys, but they are lower – in some cases significantly so – than in earlier studies focused on long Covid. The US Census' Household Pulse Survey, for instance, from June to December 2022 found that 31.1% of all Americans had ever had long Covid.
The US Department of Health and Human Services estimates that up to 23 million people in the US have ever had long Covid.
The National Center for Health Statistics, which is part of the CDC, says the differences in data may be attributed to differences between surveys such as who received questions addressing long Covid, how the questions were presented, the language used and how each survey is administered.
There are also differences in definitions. This particular report defines long Covid as symptoms that last at least three months after a positive test or a doctor's diagnosis of Covid-19. But in August, for example, the CDC defined long Covid as symptoms lasting four weeks or more.
The data for the latest study comes from the National Health Interview Survey, a nationally representative household survey of the US civilian noninstitutionalized population that's done continuously throughout the year. Questions about long Covid were added in 2022.
The majority of people in the US had had Covid by the time of the new survey, according to data from the 2022 Nationwide Commercial Laboratory Seroprevalence Survey. As of December, 91.9% of children and 77.5% of people 16 and older had antibodies indicating a previous Covid infection.
The demographics of those who reported having long Covid in the new survey were mostly consistent with previous research.
Long Covid was most likely in women, Hispanic people, adults who lived in rural areas and adults ages 35 to 49. Asian adults were the least likely to have long Covid, as were people whose family income was 400% more than the federal poverty level.
In children, long Covid was most likely in girls, children ages 12 to 17 and Hispanic kids. Asian children were again the least likely to have any long Covid symptoms.
Long Covid creates a higher burden of disability than either heart disease or cancer, an earlier study showed. Although the percentage of adults reporting long Covid has been declining over time, long-term symptoms can still be debilitating.
In response to the need for better understanding and treatment, the US Health and Human Services Department awarded first-of-its kind $45 million in grants last week to expand access to care and foster best practices for long Covid management. In July, the Biden administration announced the formation of the Office of Long Covid Research and Practice, as well as the launch of clinical trials.
Research like the new survey is important so doctors know how closely to watch for long Covid, said Dr. Amy Edwards, an infectious disease expert who runs a long Covid clinic at UH Rainbow Babies Hospital in Cleveland. Until there is a biomarker test to definitively spot the condition, it will be difficult to totally assess exactly how many people have it.
"I think this was a good stab at it," said Edwards, who was not involved in the new survey. "It is consistent with the idea that it's probably rarer with children than with adults."
One concern with the survey, though, is that it not all the respondents may even know they have had long Covid. Some people may associate it with classic symptoms like a runny nose, she said. But at Edwards' long Covid clinic, kids are coming in with other things like neurocognitive changes and constant fatigue.
Edwards is also seeing patients who have classic long Covid symptoms but only develop them after being sick with something else, like the flu or strep.
"Our hypothesis is that Covid makes some sort of change, but it's subtle enough that the patient tolerates it until it's put under some sort of additional stress," Edwards said. "Our suspicion is that it's not the flu or step that's causing classic long Covid symptoms. It's the flu or strep that's unmasking the damage that Covid had done."
Regardless of the number, Edwards said, she hopes people won't dismiss long Covid if, at least on paper, a relatively small proportion of the country seems to have it. Some of her young patients have so little energy that they can no longer go to school. If they do, they must go home and sleep rather than taking part in previous hobbies like playing soccer or joining the chess team.
"Disabling 1% of our pediatric population is not nothing," Edwards said.
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