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Your Guide To Adult Vaccines

Why Older Adults Are More at Risk for Severe Breakthrough Infections

Catching a serious case of COVID is rare if you’re vaccinated, but older adults bear the burden  

Older woman in the hospital with COVID, wearing a face mask.


En español | The coronavirus vaccines are still working extremely well, research shows, even in the era of the dangerous delta variant. Unvaccinated individuals are more than 10 times as likely to be hospitalized with COVID-19 and more than 10 times as likely to die from the disease as vaccinated people, according to a new report from the Centers for Disease Control and Prevention (CDC).

But on the rare occasion that a vaccinated person does fall seriously ill with COVID-19 — it’s happened to about 0.008 percent of the 176 million fully vaccinated Americans — it’s likely to be an older adult. About 70 percent of breakthrough infections that have required hospitalization have been in adults 65 and older, the latest CDC data shows. This population also accounts for 87 percent of breakthrough deaths.

A study recently published in The Lancet Infectious Diseases mirrors the CDC’s findings: The median age of a small group of seriously ill, yet fully vaccinated, patients hospitalized with COVID-19 at the Yale New Haven Health System between March and July was 80.5 years. Another paper, yet to be peer reviewed, tracks similar trends.

Chronic diseases, delta and dwindling immunity are likely to blame  

Throughout the pandemic, older adults have been more likely to suffer from COVID complications than their younger peers, and experts say the same reasons that made them more susceptible from the get-go could be causing them to bear the burden of severe breakthrough cases, although research is ongoing.

Take, for example, underlying health conditions, which affect about 80 percent of older Americans. Many chronic diseases put people at greater risk for a serious case of COVID-19, and emerging research shows these illnesses can still be a disadvantage even after vaccination.

Older adults also have a less robust immune system than younger people, and the protection afforded by the vaccines may wane faster for them because of it, says Mark K. Slifka, an expert in vaccine development and the longevity of vaccine-induced immune responses at Oregon Health & Science University.

Add to the mix the fact that Americans 65 and older were first in line to get their shots last year, says Jill Foster, M.D., a pediatric infectious disease physician at the University of Minnesota Medical School, and that it’s not unusual for vaccines to fall from their peak efficacy as time goes on. Plus, now we’re dealing with the highly contagious delta variant, which “is just different enough from the virus that the vaccine was developed for that you also need to have super-extra-high amounts of antibodies to fight it,” Foster adds.

A recent CDC report found that overall, the vaccines have been 86 percent effective at preventing hospitalization from COVID-19 during delta’s dominance; among adults 75-plus, that number drops to 76 percent. This gap is one reason health officials are considering booster shots for older adults as early as this fall, pending all the necessary approvals.

Boosters could change the trends  

 If the boosters do get the green light and another shot is recommended, don’t think of the vaccines as falling short of expectations.

“These vaccines continue to provide very secure protection against severe disease,” says William Schaffner, M.D., a professor in the Division of Infectious Diseases at Vanderbilt University School of Medicine. More than 90 percent of people who wind up in the hospital with COVID-19 are unvaccinated, CDC Director Rochelle Walensky, M.D., confirmed in a recent briefing.

An additional dose, however, could “maximize vaccine-induced protection and prolong its durability,” health officials say, helping high-risk populations mount an even stronger defense against COVID’s wrath. Research out of Israel, which started administering booster shots to its older population over the summer, shows the booster significantly reduced the risk of infection and severe disease.

“So it can kind of reset that clock in terms of protection,” Slifka adds. “And we should see the same thing here.”

‘It continues to be a time to be cautious’

Given that older adults are more likely to experience these severe breakthrough cases than younger populations, practicing a few extra precautions doesn’t hurt, experts say.

For example, Schaffner — who is fully vaccinated but says, “I have gray hair myself” — runs errands early in the morning when crowds are less dense and avoids large group events indoors. He also wears a mask in indoor public settings, which the CDC recommends regardless of vaccination status.

Who is at highest risk?

large study published in the British Medical Journal identified populations in the U.K. at greatest risk for hospitalization or death from COVID-19, post-vaccination. They include:

  • Individuals who are immunosuppressed from chemotherapy, a recent bone marrow transplant or solid organ transplant, or HIV/AIDS
  • People with neurological disorders, including dementia and Parkinson’s
  • Nursing home residents
  • People with chronic conditions, including Down’s syndrome, kidney disease, sickle cell disease and liver cirrhosis

Source: BMJ

Being older and having a chronic health condition — such as heart disease, lung disease, diabetes or obesity — “those things stack the cards a little bit in favor of you getting severe disease, should you become infected,” Schaffner says. “All of those people should be taking care because this virus at the moment is still this delta variant, and it is still out there spreading substantially in most communities in the United States. So it continues to be a time to be cautious.”

The key, Slifka says, is to be mindful of your own health conditions when making plans — whether that’s a trip to the grocery store or a gathering with friends — because everybody’s risk is going to look a little bit different. And if you have questions about where you stand on that spectrum, “it's a good time to just have that conversation with your doctor,” Slifka says.

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Maintaining some sense of flexibility is also important, notes Hyung Chun, M.D., a cardiologist and associate professor at Yale School of Medicine, who coauthored the Lancet study on breakthrough infections. “It's such a fluid situation. We're still in the process of really finding out about COVID itself, as well as the efficacy of vaccines and other treatments,” he says. Meaning the safeguards recommended today could look a little different a few months down the road, depending on the science.  

Finally, if you are not vaccinated, “get your vaccine as quickly as possible,” Schaffner says. Doing so will significantly decrease your odds of getting sick with COVID-19, and it will also help prevent future breakthrough cases from happening to others. “The more people who are vaccinated, that will diminish the circulation of the virus, and the virus will have fewer chances to create both serious and milder infections,” Schaffner says.

Rachel Nania writes about health care and health policy for AARP. Previously she was a reporter and editor for WTOP Radio in Washington, D.C. A recipient of a Gracie Award and a regional Edward R. Murrow Award, she also participated in a dementia fellowship with the National Press Foundation.