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For nearly three years, scientists have been working tirelessly to unravel the mysteries of the long-running COVID-19, while a growing number of people struggle with its persistent and life-altering symptoms.
It is formally known as post-COVID-19 conditiona constellation of 200 or more medical problems that can persist or begin months after an initial infection, ranging from fatigue to shortness of breath to a feeling of “brain fog.”
For some, the long COVID may mean several months of frustration. For others, it leads to debilitating health impacts that never seem to resolve. This range of possibilities leaves many patients wondering: How long does COVID really last?
A new large-scale study from Israel is the latest research to investigate the spectrum of symptoms, who is affected and for how long.
Published Wednesday in the British Medical Journalthe peer-reviewed research analyzed nearly two million medical records and matched about 300,000 people who had laboratory-confirmed infections with another 300,000 who did not test positive for SARS-CoV-2.
The researchers found that several types of health problems after a mild case of COVID persisted for several months but cleared up within the first year after an infection.
Some symptoms, such as weakness and shortness of breath, were more likely to persist.
“There are patients who experience long-term symptoms of COVID for a year and their life changes, and they suffer, we know that,” said Dr. Maytal Bivas-Benita, a senior researcher at the KI Research Institute in Kfar Ill, Israel.
“But when we look at this large population and look at their medical records, what we see is a small number of symptoms that persist, and we see that they decrease over time.”
LOOK | Most long-term symptoms of COVID disappear within a year, new research suggests:
Most long-term symptoms of COVID disappear within a year, new research suggests
New research from Israel suggests that most long-term COVID symptoms disappear within a year, but some, such as weakness and trouble breathing, are more likely to persist.
Breathing problems, weakness is more likely to persist
The research looked at dozens of different health impacts related to long-term COVID, including rashes, dizziness, hair loss, heart palpitations, chest pain, and abdominal pain.
The team also divided their findings into two time periods: the first three to six months after an infection and the following six months.
The most common post-Covid health problem? Difficulty breathing, according to the study.
But it wasn’t the only common complaint. Others, including hair loss, only lasted for the first few months after an infection, the findings suggest, while breathing problems, weakness, dizziness and a feeling of brain fog were among those that persist up to a year.
“They’ve looked at each other, too [being] “vaccinated versus not,” said Dr. Angela Cheung, a clinician and scientist at the University Health Network, who treats long-term COVID patients at a Toronto clinic. “And those who were vaccinated also have fewer symptoms, specifically the problem of shortness of breath.”
This is not the first study to suggest that vaccination can reduce long-term risks of COVID. earlier American research, published in the journal Nature Medicine last Mayfound that vaccination can reduce the likelihood of long-term COVID by about 15 percent.
The findings do not include Omicron
Indeed, research, like all scientific studies, has its strengths and weaknesses.
The large amount of medical records gave the team the ability to compare people with SARS-CoV-2 infections to an uninfected control group, so they could match subjects based on factors such as their age and conditions pre-existing health conditions. Doing so allowed the team to figure out which symptoms were most likely caused by the infection itself.
“You want to see the difference that COVID added,” said Barak Mizrahi, another senior researcher at the KI Research Institute, who worked on the study.
On the other hand, his colleague Bivas-Benita stressed that the use of medical history could also mean that the results are an underestimation of people with unresolved health problems, as those who they did not seek medical attention. (The researchers also excluded hospitalized patients to focus on mild infections.)
In the paper, the researchers also noted that there may have been underreporting of symptoms in later periods of the study.
And importantly, the study period only extended from March 2020 to October 2021, so the findings do not include the currently circulating variant of Omicron that caused a large wave of cases in Canada in early 2022.
“This study looked primarily at the Delta variant time frame, and not at Omicron,” Cheung said.
“People get better with time”
While the data may be early in the pandemic, several Canadian COVID researchers, who were not involved in the study, say it adds another piece to the puzzle.
“Yes, it’s retrospective, yes, it’s from medical records, but what it shows us is that people get better over time, which is important for people to remember,” said Cheung, who also added that some of his patients have remained with post-COVID health impacts for more than two years.
Most important, says McMaster University immunologist Manali Mukherjee, is the Israeli team’s use of a control population of those who were not infected, within a large sample size.
“This is exactly the kind of study you need,” he said.
The findings follow Mukherjee’s own research, published in the journal European Respiratory Medicine last fall.
Using a much smaller sample of roughly 100 patients in Canada, Mukherjee’s team showed that roughly three-quarters of those infected with SARS-CoV-2 recovered within a year, regardless of the severity of their illness, while others faced continued symptoms of cough, fatigue and shortness of breath.
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Long COVID needs much more study, WHO says
More research is needed to understand the scale and burden of long-term COVID and how to help with patient rehabilitation, says Maria Van Kerkhove of the World Health Organization.
But this study was also limited by its small sample size and, like the Israeli paper, only examined a period of time before Omicron’s arrival.
Mukherjee’s research also found that patients with persistent symptoms had antibodies associated with autoimmune diseases and elevated levels of cytokines, small proteins that are a key part of the body’s cellular communication network, which can trigger inflammation.
In a call with CBC News, Mukherjee, a long-time COVID sufferer herself, said this is just one of many possible mechanisms being explored to explain the range of long-running COVID symptoms. while others are looking at possible ripple effects from problems like small blood clots.
“The reason you have so many different theories is because you have so many different presentations of it,” he said.
Long-term COVID rates are likely to drop
Many presentations, different time periods, and a range of severity all make studying long-term COVID a challenging proposition.
The new Israeli research notably avoided any breakdown of exactly what percentage of people recover within a year and what percentage do not. Doing so, the researchers said, was not the goal, nor an easy thing to do given the broad spectrum of post-COVID diseases.
So far, there are a large number of people affected. The World Health Organization (WHO) maintains about 10 to 20 percent of people infected with SARS-CoV-2 can develop symptoms that can be diagnosed as long as COVID. Other estimates over the years have ranged from a small percentage of cases to 30 or 40 percent.
As CBC News previously reporteda growing body of research reassuringly suggests that long-term rates of COVID are now lower than previously thought, likely thanks to increased levels of immunity through vaccinations.
LOOK | Doctors try to understand the long COVID:
Doctors are looking to solve COVID for a long time while patients struggle to recover
Nearly two years into the COVID-19 pandemic, doctors and health experts are scrambling to find a cause and treatment for prolonged COVID-19, while patients simply struggle to recover.
Early findings using self-reported application-based data from a UK team found a reducing the odds of long COVID with the Omicron variant compared to Delta.
Similarly, a Canadian survey on COVID showed that while 26% of adults reported symptoms for at least three months after infection before December 2021, which dropped to 11 percent after December 2021 — although in both cases, the self-reported data have limitations, and neither contains a year or more of patient reports to show long-term impacts.
With so much to understand about this condition, WHO calls for continued global funding and research.
“There is much more work to be done in this space, including recognition, research and rehabilitation,” WHO’s technical lead for COVID-19, Dr Maria Van Kerkhove, said on Wednesday in response to a asked CBC News on Wednesday.
Katy Mclean, a 44-year-old Vancouver resident who has been struggling with a long list of COVID symptoms since contracting the virus in September 2020, hopes any study showing most people recover won’t deter those researchers to further study this condition. .
More than two years after she first fell ill, Mclean still struggles with fatigue and weakness, relies on a cane and has been unable to return to work.
“My biggest concern would be that the pandemic continues and that more and more people end up in my shoes, and there is no answer,” he said.