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  • Some people with lingering COVID symptoms find relief after receiving the COVID-19 vaccine.
  • A new UK study found evidence that after a vaccine people with long COVID-19 may feel better.
  • But more research is needed to know if it’s really the vaccine helping.

All data and statistics are based on publicly available data at the time of publication. Some information may be out of date.

Many people experience COVID-19 symptoms for weeks or months after their initial infection goes away. Some of these people, known as “COVID long haulers,” had only mild or no symptoms during their initial infection.

Studies suggest that anywhere from 10 percent to 30 percent of people who recover from a coronavirus infection will develop so-called long COVID, with ongoing symptoms such as fatigue, shortness of breath, “brain fog,” sleep disorders, fevers, gastrointestinal symptoms, anxiety, and depression.

Adding a twist to this, Facebook and Twitter are filling up with stories of long haulers who report, to their own surprise, that their long-COVID symptoms improve after getting a COVID-19 vaccine.

An informal survey of 450 people by Survivor Corps, a patient advocacy group for people with long COVID, found that 171 people said their condition improved after vaccination, reports The Washington Post.

While these are mysteries right now, scientists are already working to unravel them.

With over 109 million Americans fully or partially vaccinated against COVID-19, more stories of long-COVID symptoms improving after vaccination will likely surface.

But additional research is needed to understand what’s really going on here.

“Thus far [this issue is] anecdotal,” said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, at a hearing of the House Energy and Commerce subcommittee on March 17.

“Many people spontaneously get better anyway, and if you get vaccinated and you get better, you’re not sure whether it’s the vaccine or the spontaneous recovery. So you’ll have to do a randomized trial to determine that.”

A recent preprint study out of the United Kingdom, which has not yet been peer reviewed, offers additional evidence that vaccination may help people with long COVID.

Researchers followed 66 hospitalized COVID-19 patients who had symptoms that lingered for up to 8 months — including 44 who got vaccinated and 22 who didn’t.

People who received a COVID-19 vaccine had a “small overall improvement” in long-COVID symptoms when compared to unvaccinated patients.

About 23 percent of vaccinated patients reported that their symptoms improved, compared to around 15 percent of unvaccinated people. Also, fewer vaccinated people saw a worsening of their symptoms.

Researchers saw no difference in response between people who received the Pfizer-BioNTech or the Oxford-AstraZeneca vaccine.

This study was observational, so it can’t show that the vaccines were responsible for the improvement in long-COVID symptoms. Other factors could have affected the results.

Larger studies are needed, including the kind of randomized trial that Fauci mentioned in the House Energy and Commerce subcommittee hearing.

This might involve randomly assigning people with long COVID to receive the COVID-19 vaccine at the start of the study or to wait a few months. This would allow researchers to compare the vaccinated and unvaccinated groups to see if there are real differences in how their symptoms change — both after vaccination and on their own.

The National Institutes of Health recently received $1.15 billion from Congress to study the long-term health consequences of COVID-19. Fauci said this will be used to study how many people are affected by long COVID and the underlying mechanisms of this condition.

Dr. Joann Elmore, a professor of health policy and management at the UCLA Fielding School of Public Health, said research also needs to be done to clearly define long COVID, or post-acute sequelae of SARS-CoV-2 infection (PASC), as it’s officially known.

“I’m seeing patients whose loss of sense of smell — anosmia — is still present 5 to 6 months later,” she said. “That’s certainly a long-term effect.”

Other lingering symptoms after COVID-19 — such as headache, chronic fatigue, or other neurological issues — are more difficult to attribute to long COVID, because they can be caused by many things.

“The last year has been tough on all of us, and social isolation has led to a lot of fatigue and depression in patients,” Elmore said.

So, “how do I know if patients’ headaches or fatigue are due to persistence of the virus or an inflammatory reaction [to the virus], versus people getting headaches or fatigue for some other reason?”

The challenge for scientists is to tease apart the effects of the virus, the body’s reaction to the virus, and other possible causes of physical symptoms.

Elmore and her colleagues hope to do just that.

They are running a study in which they will compare two groups of people — those who have had COVID-19 and those who never tested positive for the coronavirus.

“We’re asking people at the time of their COVID test what their prior medical issues are,” she said, “and then we’re going to follow people forward and see who develops new symptoms.”

They will also compare people who were hospitalized in the ICU for COVID-19 to people who received ICU care for other conditions to see if some of their symptoms may be related to the intensive care they received rather than the virus itself.

On top of this, they are now tracking which people get the COVID-19 vaccine, which should give them data on whether the vaccines help people with long COVID.

It’s not clear why the vaccine might reduce long-COVID symptoms, but Yale immunologist Akiko Iwasaki, PhD shared two possibilities with CNBC.

People with lingering symptoms of COVID-19 could still have live coronavirus in their body, what’s known as a “viral reservoir.” The strong immune response induced by the COVID-19 vaccine may eliminate any remaining virus, which would reduce symptoms.

Another possibility is that COVID-19 may cause an autoimmune disease in some people, in which immune cells mistakenly attack the body’s own cells. In this case, the vaccine may provide “temporary relief” from an inappropriate immune response.

This might explain why some people who felt better after vaccination found that their long-COVID symptoms returned after a few weeks.

A group of Spanish researchers suggested in a recent preprint study that both the antiviral and immune modulating effects of the vaccine may be involved in relieving long-COVID symptoms.

Right now, though, these are just hypotheses that need to be tested.

Iwasaki said that she is planning a study, in collaboration with Survivor Corps, in which her team will analyze blood samples from people with long COVID before and after they get vaccinated. This may provide insight into whether the vaccines really are helping.

Whether or not vaccines relieve symptoms of long COVID, people who have recovered from COVID-19 can safely get vaccinated.

There are also benefits to getting vaccinated, because it’s not clear how long the immune protection from having COVID-19 lasts.

“I am recommending that everyone get vaccinated, whether they’ve had COVID or not,” said Elmore.

The Centers for Disease Control and Prevention (CDC) recommends that people wait to get vaccinated until after they have fully recovered from the short-term symptoms of COVID-19.

If local vaccine doses are in short supply, the CDC says people who have had COVID-19 can temporarily delay vaccination in order to give people with no protection a chance to get vaccinated.