Vaccines help older people more than we knew

Let’s be clear: The main reason to get the shingles vaccine is that two shots provide at least 90 percent protection against a painful, blistering disease that one-third of Americans will suffer from in their lifetime, one that can cause persistent nerve pain and other unpleasant long-term consequences.

The most important reason why older adults get vaccinated against RSV respiratory infection is that their risk of being hospitalized for this infection decreases by almost 70% in the year they receive the vaccine, and by almost 60% over two years.

And the main reason to roll up your sleeves for an annual flu vaccine is that when people become infected, it also reliably reduces the severity of illness, although its effectiveness varies depending on how well scientists have predicted which flu strain will emerge.

But there are other reasons why older people want to be vaccinated. They’re known, in medical parlance, as off-target benefits, meaning the shots do good things beyond preventing the diseases they were designed to prevent.

The list of untargeted benefits grows as “research has accumulated and accelerated over the last 10 years,” said William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center in Nashville, Tennessee.

Some of these protections have been established by years of data; others are the subject of more recent research, and the results are not yet as clear. The first vaccines against RSV, for example, were not available until 2023.

Still, the results “are really very consistent,” said Stefania Maggi, a geriatrician and senior researcher at the National Research Council’s Institute of Neuroscience in Padua, Italy.

She is the lead author of a recent meta-analysis, published in the British journal Age and Aging, which found reduced risks of dementia after vaccination against a range of diseases. Given these “downstream effects,” she said, vaccines “are key tools to promote healthy aging and prevent physical and cognitive decline.”

Yet too many older adults, whose weakened immune systems and high rates of chronic disease put them at higher risk of infectious diseases, have missed out on vaccination.

The Centers for Disease Control and Prevention reported last week that about 31% of seniors have not yet received a flu vaccine. Only about 41% of adults 75 and older had ever been vaccinated against RSV, or respiratory syncytial virus, and about a third of older adults had received the most recent covid-19 vaccine.

The CDC recommends the one-time pneumococcal vaccine for adults 50 and older. An analysis in the American Journal of Preventive Medicine, however, estimates that from 2022, when new guidelines were published, through 2024, only about 12% of those ages 67 to 74 received them, and about 8% of those 75 and older.

The strongest evidence of untargeted benefit, dating back 25 years, shows a reduction in cardiovascular risk following the flu vaccine.

Healthy older people vaccinated against influenza have significantly lower risks of hospitalization for heart failure, pneumonia and other respiratory infections. Flu vaccination has also been linked to lower risks of heart attack and stroke.

Additionally, many of these studies predate the more potent flu vaccines now recommended for older adults.

Could the RSV vaccine, which protects against another respiratory disease, have similar cardiovascular effects? A recent large Danish study of older people found a nearly 10% drop in hospitalizations for cardiorespiratory problems – involving the heart and lungs – among vaccinated people compared to a control group, a significant decrease.

The decline in rates of cardiovascular hospitalizations and strokes, however, did not reach statistical significance. This may reflect a short follow-up period or inadequate diagnostic testing, cautioned Helen Chu, an infectious disease specialist at the University of Washington and co-author of an accompanying editorial in JAMA.

“I don’t think RSV behaves any differently than the flu,” Chu said. “It’s just too early to have information on RSV, but I think it will show the same effect, maybe even more.”

Vaccination against another dangerous respiratory disease, covid, has been associated with a lower risk of developing long covid, with its adverse effects on physical and mental health.

Perhaps the most provocative findings concern vaccination against shingles, also called herpes zoster. Researchers made headlines last year when they documented an association between shingles vaccination and lower rates of dementia – even with the less effective vaccine that has since been replaced by Shingrix, approved in 2017.

Almost all studies of off-target benefits are observational, because scientists cannot ethically withhold a safe and effective vaccine from a control group whose members might then become infected with the disease.

This means that such studies are subject to “healthy volunteer bias,” because vaccinated patients may also adopt other healthy habits, differentiating them from those who are not vaccinated.

Although researchers attempt to control for various potentially confounding differences, ranging from age and gender to health and education, “we can only say that there is a strong association, not cause and effect,” Maggi said.

But Stanford researchers took advantage of a natural experiment in Wales in 2013, when the first shingles vaccine, Zostavax, became available to older people who were not yet 80 years old. Anyone who reached it was ineligible.

Over seven years, dementia rates among eligible vaccination participants fell by 20% – even though only half had actually received the vaccine – compared to those who narrowly missed the threshold.

“There is no reason why people born a week earlier were different from those born a few days later,” Maggi said. Studies in Australia and the United States have also found a reduced risk of dementia following a shingles injection.

In fact, in the meta-analysis published by Maggi and his team, several other childhood and adult vaccinations appear to have such effects. “We now know that many infections are associated with the onset of dementia, whether Alzheimer’s disease or vascular,” she said.

In 21 studies involving more than 104 million participants in Europe, Asia and North America, shingles vaccination was associated with a 24% reduction in the risk of developing dementia. Flu vaccination was associated with a 13% reduction. People vaccinated against pneumococcal disease had a 36% reduction in Alzheimer’s risk.

The Tdap vaccine against tetanus, diphtheria and pertussis (cough) is recommended for adults every 10 years, with vaccination of the elderly often prompted by the birth of a grandchild, who may not be fully vaccinated for months. This was associated with a one-third reduction in dementia.

Other researchers are studying the effects of shingles vaccination on heart attacks and strokes and of covid vaccination on cancer survival.

What causes such vaccine bonuses? Most hypotheses focus on inflammation that occurs when the immune system mobilizes to fight an infection. “You have environmental damage” in the body, “and it takes time to calm down,” Chu said.

The effects of inflammation can last much longer than the initial illness. This can allow other infections to take hold or cause heart attacks and strokes when clots form in narrowed blood vessels. “If you prevent infection, you prevent this other damage,” Chu said.

Hospitalization itself, during which elderly patients may become deconditioned or develop delirium, is a risk factor for dementia, among other health problems. Vaccines that reduce hospitalizations could therefore delay or prevent cognitive decline.

Trump administration health officials are more vocal about vaccines for children than vaccines for adults, but their vocal opposition could also contribute to inadequate vaccination among older Americans.

Not only will many not benefit from the new untargeted benefits, but they will remain vulnerable to the diseases that vaccines prevent or mitigate.

“Current national immunization policy is uncertain at best and, in some cases, appears anti-vaccine,” said Schaffner, a former member of the CDC’s advisory committee on immunization practices. “All of us in public health are very, very distressed. »

“The New Old Age” is produced through a partnership with The New York Times.

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