Three years after the pandemic and more than 100 million COVID cases in the US, little is known about the answer to this question: When someone becomes infected today, what is their risk of developing Long Covid?
“Even the medical community is not clear on all of this. The data is emerging so fast and estimates vary,” said Dr. Renu Kaushal, chair of the Department of Population Health Sciences at Weill Cornell Medicine.
In the absence of definitive data on long-term Covid risk, seven researchers examining the prevalence of the condition in the US offered their best estimates to NBC News. Most said it was reasonable to assume that the current risk for vaccinated people is 10% or less, and some thought the difference was small — 5% or less.
He said that re-infection also poses a risk of Covid for a long time.
“You can get COVID a second time,” said Dr. Ziad Al-Aly, chief of research and development at Veterans Affairs St. Louis Health Care System and a clinical epidemiologist at Washington University in St. Louis.
Since the start of the pandemic, nearly 38 million adults in the US have reported post-Covid symptoms lasting three months or longer, according to an NBC News analysis of data from a household survey conducted by the Census Bureau. Survey results showed that as of February, about 11% of adults who had ever had COVID were experiencing long-term COVID.
Those figures combine vaccinated and unvaccinated cases together, although the risk profiles differ: researchers interviewed estimate that for unvaccinated people, the risk of long-term Covid is about 15% to 20%. % Is.
The US is still recording more than 225,000 new Covid cases every week, according to the Centers for Disease Control and Prevention, so Covid is an ever-present threat in the long run.
Al-Aly said, “Out of 100 people you see, 95 or 96 are going to be fine. But you could be one of those unlucky four, and I personally don’t want to take my chances.” “
The risk of long covid seems to be decreasing
Long COVID is often defined as symptoms lasting at least three months following a coronavirus infection, although symptoms are wide-ranging and vary in severity and duration. Many patients complain of fatigue, brain fog, shortness of breath, heart palpitations, and muscle, joint, or chest pain.
Overall, rates of long Covid have been going down since the Census Bureau began including questions about it in its June 2022 household survey. ,
But Sharon Saydah, a senior CDC epidemiologist who leads the agency’s post-Covid conditions team, said the survey “is not a good way to judge individual risk,” noting that it does not include new long-term Covid-19 risk factors. Cases are included and those that are already in the epidemic.
Experts offered some possible explanations for the long-term declining trend in Covid cases: the use and treatment of vaccines, and the nature of the Omicron variant.
A deluge of studies has shown that getting even a single Covid shot reduces a person’s chance of long-term symptoms, and that the risk declines further with each additional shot. The antiviral paxlovid also lowers the odds of longer Covid, according to a study awaiting peer review.
“We now have more things that can help lower your risk,” said Dr. Michael Gottlieb, an emergency medicine physician and researcher at Rush University Medical Center.
Studies have also shown a drop in long-term COVID rates following the emergence of the Omicron variant, although researchers disagree as to whether the variant itself is associated with fewer long-term health problems than its predecessors.
“Existing data suggest that long-term Covid risk may be lower in the post-Omicron era, but this is confounded by increases in vaccination rates that have essentially occurred over the same time period,” Dr. Stuart Katz, a said the principal investigator of the National Institutes of Health’s RECOVER initiative, which is studying the long-term effects of COVID.
Factors that affect a person’s long-term risk of COVID include their age, gender, health history, and the severity of their illness. According to a review in the journal Nature, the risk may be higher in women and people with type 2 diabetes or ADHD.
Kaushal said she is seeing frequent heart and kidney problems in older men who had severe Covid, as well as sleep disorders and shortness of breath in younger women.
New prolonged COVID cases may be less severe than average
There is some expectation that new cases of Long Covid will be milder than those that developed earlier in the pandemic, due to the same factors that are causing the rates to decline.
“Its incidence, its severity and its duration seem to be reducing,” Kaushal said.
Dr. Sun Yu, director of the COVID Ambulatory Monitoring Program at UCLA Health, said she still sees debilitating cases of prolonged COVID, but “in general, I’m seeing fewer and less severe versions of it.”
Katz noted, however, that the sheer number of Omicron infections may partially explain why doctors are seeing more patients with mild symptoms.
And some vaccinated people experience persistent, life-changing health problems after having COVID.
“I see these patients — some of them literally can’t even read an email. They have brain fog that’s so profound, it impairs their cognitive abilities to a great extent,” Al-Aly said.
Studies give a range of long Covid rates
Quantifying the long-term exposure to Covid is difficult for a number of reasons, and Saidah said it’s also difficult to compare rates of other post-viral illnesses, as other viruses haven’t caused this level of widespread disease over a short period of time. Are.
Studies of long COVID have defined the condition in different ways and evaluated different types of patients.
“Everyone comes up with different approaches,” said Dr. Roy Perlis, who directs the Center for Quantitative Health at Massachusetts General Hospital. “There’s the health record approach. There’s the survey approach. … They all tell us different things. None of them are right.”
One of the largest studies on the subject, from Al-Aly’s team in St. Louis, suggested that the overall risk of prolonged Covid was 4% to 7% during the first year of the pandemic.
“My hunch now is that it’s less than that,” he said.
That study examined the health records of more than 181,000 patients at the VA who had been diagnosed with COVID-19 through March 2021, then compared that group with nearly 4.4 million veterans who did not test positive.
But relying on health records may be an underestimate, because such studies only include patients who have sought medical care and been tested for COVID-19.
For this, Yu and his team at UCLA directly observed more than 1,000 COVID patients who were at high risk of severe disease or were hospitalized during the first year of the pandemic. Their study found that 30% had symptoms up to 90 days after their diagnosis or hospital discharge.
He hypothesized that the overall risk for people vaccinated today may be about 5% to 10%.
Kaushal also said, “The internal understanding is that we are close to 5%.”
Saidah said those projections “seem reasonable” given the CDC data, which puts the long COVID rate at 20% from March 2020 to November 2021. Now, he explained, “studies are showing that vaccination reduces your risk by anywhere from 20% to 50%.”
According to Katz, the RECOVER initiative’s observational study has enrolled more than 18,000 people, so it may eventually provide clear estimates of long-term Covid risk. Interim findings expected later this year may also shed light on the most general symptoms of the condition.
