You're 3 Times More Likely to Get COVID After Vaccination If You Have This

One condition seriously raises the risk of having a breakthrough infection.

By now, there's enough evidence to show that the currently available COVID-19 vaccines offer plenty of protection from the virus. A study released by the Centers for Disease Control and Prevention (CDC) in September noted that Johnson & Johnson's vaccine was 71 percent effective at preventing hospitalization from the virus, while Pfizer's and Moderna's two-dose vaccines provided 88 percent and 93 percent protection, respectively. But in the face of waning immunity over time, new variants of the virus, and specific medical conditions that may affect how the vaccines work, breakthrough infections in fully vaccinated people are still possible. Now, a new study has shed light on which people are much more likely to get COVID after vaccination.

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In a study published in the Journal of Medical Economics on Nov. 30, healthcare records from nearly 1.3 million people who had received both doses of Pfizer's mRNA vaccine were analyzed to determine the rate of breakthrough infections. Results showed the shots were incredibly effective, with 0.08 percent of fully vaccinated patients becoming infected between Dec. 10, 2020 and July 8, 2021. But the results also uncovered that those with weakened immune systems were three times more likely to have a breakthrough infection, with 0.18 percent of immunocompromised patients becoming ill compared to 0.06 percent of non-immunocompromised patients.

The researchers note that 17.7 percent of all patients surveyed were considered to have weakened immune systems, including those suffering from advanced HIV/AIDS, cancer, kidney disease, rheumatologic or other inflammatory conditions, other immune conditions, and bone marrow or organ transplant recipients. Of the 978 reported breakthrough infections, 124 of them—or 12.4 percent—required hospitalization. In that group, 74 patients—or 59.7 percent—were immunocompromised. Two patients who ultimately died from the virus also had weakened immune systems.

"While some COVID-19 vaccine breakthrough infections among those who are fully vaccinated against COVID-19 are expected, the findings of this study show that they are rare and less likely to result in hospitalization or death in those without an [immunocompromising] condition," the study's authors wrote. "However, further research is necessary to continue monitoring the rates of breakthrough infections in the general population, especially with waning duration of protection and emerging SARS-CoV-2 variants."

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The researchers concluded that their findings supported the results of other studies and suggested that a third shot should be included in the regimen for any patient with a weakened immune system. But the data also showed that the vaccines are still not completely foolproof when it comes to stopping the virus.

"Several countries are currently experiencing a resurgence of SARS-CoV-2 infections despite the rollout of mass vaccination programs," Manuela Di Fusco, the study's lead author from the Pfizer Health Economics and Outcomes Research team, said in a statement. "While COVID-19 mRNA vaccines help protect people from getting infected and severely ill, the risk of breakthrough infections in fully vaccinated people is not completely eliminated."

Mounting research has found that immunocompromised patients were more likely to suffer a breakthrough infection. One non-peer-reviewed CDC-funded study released on medRxiv in July looked at the effectiveness of the COVID vaccine in preventing virus-related hospitalizations in the U.S. The researchers analyzed 1,210 U.S. adults hospitalized between Mar. 11 and May 5, comparing COVID-positive patients with patients who tested negative for the virus. According to the study, nearly half of the hospitalized COVID patients infected after being vaccinated were immunocompromised. Of the 45 patients with breakthrough COVID infections, 44.4 percent were immunosuppressed.

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"All of the patients that have been fully vaccinated that I've admitted to the ICU have been immunocompromised. Every single one of them," Todd Rice, MD, co-author of the study and director of the medical intensive care unit at Vanderbilt University Medical Center in Nashville, Tennessee, told NBC News. He added that all of the other hospitalized COVID patients at his hospital at the time had not been vaccinated.

Currently, the CDC recommends anyone with a weakened immune system get a supplemental initial dose of vaccine to shore up their immunity. "People who are immunocompromised are especially vulnerable to COVID-19," the agency writes on their website. They advise that "moderately to severely immunocompromised people ages 18 years and older who completed their Moderna vaccine primary series should plan to get an additional primary dose 28 days after receiving their second shot," while those 12 and older should do the same with Pfizer. All immunocompromised patients are also eligible to receive a booster shot after their primary doses.

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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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