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One of the scariest aspects of COVID-19 now seems to be the possibility that symptoms can linger after infection. What is my long-term risk of COVID if I become infected? And will vaccination change that?
Over the past year, there has been a long series of published studies on COVID. Dozens of these studies attempt to estimate the risk of having symptoms that persist for many months after contracting COVID.
But when you look closely at the data, a huge contradiction emerges: Estimates of the prevalence of COVID range from less than 5% to nearly 60% of all COVID cases. So what’s happening?
“It can be really confusing, even for scientists,” Christina Pagel, who directs the Clinical Operations Research Unit at the University College of London.
One of the main problems is with the term “long COVID”. What scientists, doctors and the media have long called “COVID” is more than just a disease or disorder. “It looks like what has been grouped together as ‘long COVID’ is actually two or three different groups of disorders,” says Pagel.
Each of those disorders can have a range of specific symptoms and causes. Some affect populations differently than others, or persist for a different length of time.
Severe illness with high risk of prolonged COVID
Many early studies focused mainly on people who were hospitalized with COVID. “Obviously these people will get sicker,” said the pediatrician. Claire Steves at King’s College London. Some people spend time in the ICU or on a ventilator.
With this serious illness, there is a high risk of organ damage, be it by the virus itself or the body’s response to it. “Some people can develop scarring of the airways and a type of fibrosis from inflamed lungs,” she said.
Some people develop inflammation of the heart muscle, called myocarditis. Some have inflammation in the blood vessels or brain. “In some individuals, there is clear evidence of changes in areas of the brain that are sensitive to smell,” says Steves.
This tissue damage and inflammation can cause a range of lingering symptoms, including a rapid heartbeat, severe fatigue, breathing problems, and cognitive problems.
And organ damage can take a long time to heal, regardless of its cause. In fact, whenever a person is seriously ill in the hospital, symptoms can linger, says primary care physician and bioethicist. Dr. Zackary Berger at Johns Hopkins University.
“It is well known that people take a long time to recover from a serious illness,” says Berger. “So I think it’s not surprising that people who end up in the ICU take longer to recover.”
Studies have found that for people hospitalized with COVID, the risk of developing symptoms that persist for six months after COVID is quite high, about 50%, Steves said.
Mild or moderate disease can significantly reduce risk
Much news report has suggested that the risk of prolonged COVID after a mild or moderate infection appears similar to the risk after a severe case. Indeed, some learn found that up to 60% of people reported one or more symptoms that persisted six months after contracting SARS-CoV-2, including fatigue, brain fog, shortness of breath, chest pain, cough, joint pain and muscles, abdominal symptoms, headaches, and anxiety or depression.
But many of these studies are missing what’s called a control group. That is, they don’t take into account that these symptoms may be common in people who have not had COVID – or who have had other types of infections in the past. In other words, scientists aren’t sure if these symptoms are specifically related to COVID or are typical of recovery from many infectious diseases that have not yet been noticed.
“There is a belief that you have an infectious disease, you get treated, and it ends,” says Berger. “But for a lot of people, being sick isn’t like that.”
For example, an episode of pneumonia caused by bacteria. Antibiotics can stop the infection. But then many people suffer from symptoms for weeks afterward. “Half of people have breathing problems one month after having pneumonia,” says Berger. “A lot of people, right?
The same goes for the flu. And a study, published in September, clearly demonstrates this idea. Researchers in the UK analyzed the electronic health records of nearly 400,000 people with a confirmed flu or COVID diagnosis. They then looked at who had persistent symptoms. Nearly 60% of people with COVID have at least one symptom that lasts six months, but nearly 40% of people with the flu also have at least one persistent symptom, similar to those seen in people with COVID.
“Many people have lingering symptoms after infectious diseases,” says Berger. “I think that’s something we need to realize.”
Thus, another type of “long COVID” could be those that take longer to recover from an infection, whether it’s the flu, pneumonia, or COVID. In other words, there may have been “prolonged flu” or “prolonged pneumonia,” but it was simply not appreciated.
COVID may be a new cause for post-virus syndromes
There is growing evidence that SARS-CoV-2 can sometimes cause some post-viral syndromes, or diseases that occur after an infection. They include a Chronic fatigue syndrome, also called I / CFSand blood circulation disorders, known as orthostatic tachycardia syndrome, or JAR.
For example, a research, which included 130 patients hospitalized for COVID, found that 13% of them met the criteria for ME/CFS six months after diagnosis.
Dr. Peter Rowe at Johns Hopkins University there is evidence that mild illness can also trigger it. “We have a small sample size, but in these [patients] where the function is still impaired [six months] after contracting COVID-19 … all met the criteria for ME/CFS,” he wrote in an email to NPR. I mean patients with persistent symptoms after mild COVID-19 infection, not in the hospitalization group, or patients with more severe acute post-COVID-19 organ damage. “
More than 2 million Americans will be affected
So, after you factor in the other causes of the so-called “long COVID,” what remains may be a disorder specific to SARS-CoV-2. “There is no standard definition for this syndrome,” said the infectious disease epidemiologist Ira Longini at the University of Florida. “It’s a collection of symptoms, including shortness of breath, brain fog, fatigue, but also a problem with a specific organ or tissue, such as the heart or brain.”
The disorder may involve the virus getting into an organ or tissue and staying there, or some lingering inflammation left over from the body’s fight against the virus, Longini said.
It’s not yet known exactly what percentage of people will have these symptoms a few months after COVID, but Steves at King’s College London says she analysis showed a much lower risk in people who were not hospitalized in the UK
She said the Office for National Statistics in the UK has the best estimate, right now, of the prevalence of persistent COVID symptoms in this population. That data includes self-reports from more than one million people with a positive COVID diagnosis.
“Overall, in the population as a whole, that data shows that the prevalence of COVID persisting, more than 12 weeks after infection, is just under 5% of people,” Steves said.
Given the huge number of COVID cases in the United States (and worldwide), even a 5% rate means more than 2 million Americans (and nearly 13 million globally) will be affected by the cluster. This specific COVID symptom for at least several months (and even more will struggle with other post-virus problems).
Fortunately, Steves says, the proportion of people with these persistent COVID symptoms drops dramatically one year after infection. “There are certainly people who still have symptoms for more than a year, even up to 18 months,” she said. “But there’s a very small percentage of those people. Over time most people get better. I see it in my clinic.”
However, because so many people are affected, it’s important for healthcare workers to be on the lookout for signs of any kind of long-term COVID – and keep an open mind about it, Dr. Paddy Ssentongo, an epidemiologist at Pennsylvania State University. “Doctors have to listen to patients. They tell you what’s going on with them. They don’t produce symptoms. Patients know best what’s going on with their bodies.”
How to reduce the risk of long-term COVID
The best way to reduce your risk of getting any kind of long-term COVID is to reduce your risk of getting a severe case of COVID. And to do that, Steves says, getting vaccinated is first on the list. She and her colleagues were find that getting two doses of the vaccine halves the risk of developing COVID-specific symptoms after infection.
But the overall effect of the vaccine on your risk of any type of long-term COVID is much greater, says Longini at the University of Florida. “Vaccines reduce the probability of infection by maybe 70 percent. So overall, the sustained reduction in COVID in vaccinated people is 80 or 90 percent.
“That just shows you the power of a COVID-19 vaccine,” he added. They not only protect against acute illness, but also various chronic diseases associated with SARS-CoV-2.
