If you are vaccinated against COVID-19, there is still a possibility of infection, but a lower risk of severe sickness, or of developing long-lasting symptoms from the disease, according to experts and research.
A new preprint study — not yet peer-reviewed — from Israel published online Monday suggested that COVID-19 vaccination may have a protective effect against “long COVID” in addition to reducing the risk of acute illness.
“Vaccination with at least two doses of COVID-19 vaccine was associated with a substantial decrease in reporting the most common post-acute COVID-19 symptoms,” the study authors said.
The study included more than 3,000 individuals who filled out an online questionnaire. Among the 637 vaccinated people who got COVID-19, they were less likely to report symptoms of fatigue, headache, weakness and persistent muscle pain compared to those who were unvaccinated and infected, the study said.
More than two years into the pandemic, experts are still trying to determine the impact of long COVID — when symptoms last at least a month after a person is diagnosed with COVID-19 — and learn how to help people suffering from it. Those people are often referred to as COVID long haulers.
While the research — including this latest study — looking at the effectiveness of vaccinations on long-term symptoms is encouraging, experts say it remains inconclusive.
“I think there is a suggestion that those who are fully vaccinated are less likely to develop long COVID,” said Dr. Janna Williams, an infectious diseases specialist at Northwestern Medicine in Chicago.
This is because if you are fully immunized, the chances of contracting COVID-19 are reduced and since vaccines are highly effective at preventing severe disease, there is a smaller likelihood of developing debilitating symptoms that are associated with long COVID, she explained.
What does the science say?
Neuroplasticity expert Ashok Gupta has been researching long-haul COVID at the Gupta program, a global clinic helping people with chronic illnesses. He said this latest preprint from Israel is consistent with other studies.
“I think it’s still preliminary data, but it seems to be encouraging,” he said.
Gupta said if the body has already had a pre-warning of a coronavirus infection through vaccination and is able to recognize the virus, the body can then fend it off more effectively. And when the infection is not as severe, it may not lead to long COVID symptoms, he added.
Dr. Allison McGeer, an infectious disease physician at the Sinai Health System in Toronto, said there is some evidence that long COVID was less common in vaccinated people who got breakthrough infections with previous variants like Delta.
But the “jury is still out” on what role a person’s vaccination status can play in protecting them from long COVID, she said.
“We are seeing more of these papers and not all of the papers have this finding that there’s a substantial reduction, but I think more of them do than not,” she told Global News.
A peer-reviewed U.K. study published in the Lancet medical journal in September 2021 found that the full two-dose series of a COVID-19 vaccine reduced the risk of persistent symptoms — lasting at least 28 days post-infection among those who got COVID-19.
According to data collected by the U.K. Office for National Statistics in October 2021, a first dose of a COVID-19 vaccine was associated with a 13 per cent decrease in the likelihood of self-reported long COVID, defined by researchers as symptoms persisting for at least 12 weeks after getting COVID-19. A second shot was associated with a nine per cent decline relative to the first.
However, another preprint paper from the U.S. that analyzed more than 10,000 breakthrough cases in November 2021 suggested that at least one dose of a COVID-19 vaccine did not offer protection against long-COVID features.
Complex condition
There are limitations to the findings with selection bias and subjective reporting occurring, according to Dr. Christopher Carlsten, a professor of medicine at the University of British Columbia and the director for Legacy for Airway Health.
McGeer said none of the studies so far are conclusive and more time and research are needed.
“Long COVID is a complex condition that people are just starting to work on understanding,” she said.
“So a piece of it is, it takes time to assess it, to really understand how we make the diagnosis.”
What makes it challenging to study this condition is the fact that there is no standardized definition of long COVID, experts say.
According to the World Health Organization (WHO), “post COVID-19 condition” occurs in individuals with a history of probable or confirmed SARS-CoV-2 infection, usually three months from the onset of COVID-19, with symptoms that last for at least two months and cannot be explained by an alternative diagnosis.
Common symptoms associated with long COVID are fatigue, shortness of breath, chest discomfort, headaches, brain fog — a state of forgetfulness, poor concentration or feeling confused — memory loss, and muscle and joint pain, said Williams.
Some people may continue to test positive for COVID-19 as they suffer through long COVID, while others may not, she added.
Over the last year, experts said there have been a number of anecdotal stories about “long haulers” getting better after receiving the vaccine, but they have also heard the opposite too.
“There’s a small number of patients that feel like the vaccine has cured them of their illness, although that’s not persistent in all cases, either,” Dr. Jesse Greiner, medical director of the Post-COVID-19 Recovery Clinic at St. Paul’s Hospital in Vancouver, told Global News in December.
“It’s difficult to say because there’s still so much that we don’t understand about how long COVID works,” he said.
Despite the unanswered questions, Williams said everyone should get vaccinated, adding there is no detriment to the shots for those suffering from long COVID.
“Preventing the acquisition of COVID upfront is your best protection of preventing long COVID,” she said.
— with files from Jamie Maraucher and Robin Gill