This Is How Likely You Are to Develop Long COVID—Even If You're Vaccinated

A new study has shed some light on how often patients develop lingering symptoms.

Mounting research is beginning to paint a clearer picture of how likely breakthrough infections are to occur in people who are fully vaccinated—and how effective the shots are at preventing hospitalization or death from the virus. But even as we begin to better understand how well existing vaccines can protect us from new variants such as Delta, relatively little information is available when it comes to breakthrough infections and long-term effects of the disease. Fortunately, a new study sheds some light on how likely it is for fully vaccinated people to develop long COVID, The New York Times reports.

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The latest research, published in the New England Journal of Medicine on July 28, focused on a group of 1,497 fully vaccinated healthcare workers in Israel. Among the group, 39 breakthrough infections were reported—which amounts to 2.6 percent—with most cases showing only mild or no symptoms. But researchers found that seven out of 36 healthcare workers—or 19 percent–who were followed up with six weeks after infection still reported lingering symptoms associated with long COVID, including weakness, fatigue, loss of smell, cough, and muscle pain, The Times reports.

However, the study's authors immediately cautioned against drawing too many conclusions from the results. Besides the small sample size, the study itself was also designed to test antibody levels in those with breakthrough infections, not to assess the risk of developing long COVID for fully vaccinated people. Still, some experts view the findings as reason enough to continue to be cautious to avoid infection.

"I'm going to take it at face value that one in five people, six weeks after a breakthrough case, continued to feel crummy," Robert M. Wachter, MD, professor and chair of the department of medicine at the University of California, San Francisco, told The Times in regards to the research. "That's enough to make me want to wear two masks when I go into the grocery store, which is not that burdensome anyway."

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Although scant scientific research is available on the topic besides the Israeli study, there has been some other informal data collected. Recently, a team of researchers working with Survivor Corps, an organization providing support and resources to people with long COVID, launched a new poll on Facebook targeting people who got COVID after they'd been vaccinated. The survey presented to the approximately 169,900-member group received responses from nearly 2,000 fully vaccinated participants by the cut-off date of July 22nd.

Preliminary results of the ongoing poll, which were posted on medRxiv on July 25, found that of these initial respondents, 44 reported symptomatic cases of COVID after being fully vaccinated with either Pfizer, Moderna, or Johnson & Johnson. More than half of those with breakthrough infections—or 24 respondents—reported experiencing symptoms of long COVID.

Among the 44 breakthrough COVID patients who responded to the survey, 19 were Pfizer recipients, 12 of whom said their infection led to long COVID; 17 were Moderna recipients, with six reporting their infections resulted in long COVID; and eight got the Johnson & Johnson vaccine, six of whom said they subsequently developed long COVID. Of all the respondents, only one said their breakthrough infection led to both long COVID and hospitalization.

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Similar to the Israeli study, researchers from the Survivor Corps survey emphasized that further "rigorous and detailed studies" would be needed before any conclusions could be drawn. "The poll was limited and the respondents highly self-selected, so it is not possible to estimate rates of breakthrough or subsequent risk of long COVID," the researchers wrote of the survey results.

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Currently, the U.S. Centers for Disease Control and Prevention (CDC) only records breakthrough infections that lead to hospitalization or death, which some experts argue makes it nearly impossible to ascertain what might be happening in the real world. "It's very frustrating not to have data at this point in the pandemic to know what happens to breakthrough cases," Akiko Iwasaki, PhD, an immunologist at Yale School of Medicine who is conducting studies of long COVID, told The Times. "If mild breakthrough infection is turning into long COVID, we don't have a grasp of that number."

Still, other experts point out that regardless of missing data, being fully vaccinated will bring down the number of overall cases and long COVID in the end. "It's simple math," Athena Akrami, a neuroscientist at University College London who has been collecting and publishing data on long COVID patients, told The Times. "If you reduce infections, then the likelihood of long COVID will drop automatically."

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Zachary Mack
Zach is a freelance writer specializing in beer, wine, food, spirits, and travel. He is based in Manhattan. Read more
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