For a majority of people, the COVID vaccine doesn’t cause adverse health effects — but a small percentage experience chronic symptoms that can last for months or even years. 

Yale researchers recently made some discoveries about why certain people experience this condition, which they have dubbed “post-vaccination syndrome” (PVS).

In early findings, the team recognized “potential immunological patterns” that are unique to people with PVS. The hope is that this discovery will help to enable future treatments and therapies for those who are affected.

“This work is still in its early stages, and we need to validate these findings,” said co-senior study author Akiko Iwasaki, Sterling Professor of Immunobiology at Yale School of Medicine, in a press release.

“But this is giving us some hope that there may be something that we can use for diagnosis and treatment of PVS down the road.”

Symptoms of post-vaccination syndrome

People with this condition may suffer from excessive fatigue, exercise intolerance, brain fog, insomnia and dizziness, according to the Yale researchers. 

These typically develop within a day or two of vaccination and can worsen over time.

“It’s clear that some individuals are experiencing significant challenges after vaccination. Our responsibility as scientists and clinicians is to listen to their experiences, rigorously investigate the underlying causes, and seek ways to help,” said co-senior author Harlan Krumholz, professor of cardiology at YSM, in the release.

“Post-vaccination syndrome is real, and has been found [to occur] from many vaccines, including COVID,” Dr. Marc Siegel, clinical professor of medicine at NYU Langone Health and Fox News senior medical analyst, told Fox News Digital.

What the study found

The researchers analyzed blood samples from 42 study participants who experienced symptoms of PVS and 22 who did not.

Those with symptoms were shown to have lower levels of two types of white blood cells. People with PVS who had never had COVID also had lower levels of antibodies against the SARS-CoV-2 spike protein, likely because they tended to have fewer vaccine doses, according to the release.

“Post-vaccination syndrome is real, and has been found [to occur] from many vaccines.”

Dr. Marc Siegel

“Fewer vaccine doses and no viral infection means the body’s immune system has had little opportunity to develop a defense to the virus,” said the researchers.

Some of the people with PVS also had higher levels of the SARS-CoV-2 spike protein, which enables the virus to penetrate and infect host cells. This has also been linked to a higher risk of developing long COVID.

“We don’t know if the level of spike protein is causing the chronic symptoms, because there were other participants with PVS who didn’t have any measurable spike protein — but it could be one mechanism underlying this syndrome,” said Iwasaki.

In addition to the elevated spike proteins, other factors could increase the risk of post-vaccination syndrome. Those include autoimmunity, tissue damage and reactivation of Epstein-Barr virus (EBV), the researchers wrote.

“Akiko Iwasaka is a world-renowned immunologist at Yale who has studied COVID (and COVID vaccines) extensively,” Siegel pointed out. 

“In this new study, she reports that in a very small percentage of those who received COVID vaccines (and experienced prolonged side effects), there may be the presence of persistent spike protein,” Siegel confirmed.

“They may also experience immune disruption, which takes the form of elevations in inflammatory immune cells (CD8 and TN alpha) and a decrease in cells that help resolve inflammation and infection (CD4 helper cells).”

The researchers agreed that more studies are essential to guide diagnosis and treatment.

“We’re only just starting to make headway in understanding PVS,” said Krumholz. “Every medical intervention carries some risk, and it’s important to acknowledge that adverse events can occur with vaccines.”

“Our focus must remain on understanding what these people are experiencing through rigorous science and addressing the needs of those affected with compassion and an open mind.”

Siegel agreed, adding, “This needs to be further studied in terms of understanding how common prolonged COVID vaccine side effects are and how to predict them and treat them.”

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