By the year 2030, one-quarter of all people alive will be at least 60 years old. You've heard that 60 is the new 40, and in some respects that's certainly true. But when it comes to fighting off infectious disease, "60 is the new 59" might be more like it.
"Aided by improved sanitation and antibiotics, vaccines have vastly reduced the toll of infectious diseases, enabling kids to grow up - and, eventually, to grow old," I wrote in a 2009 Stanford Medicine article about this subject.
The trouble is, the older we get the weaker our immune systems tend to become. Infectious diseases we could have fought off with ease in our youth become life-threatening in old age. Adding insult to injury, vaccines that work fine in younger people don't always get the job done among seniors.
In a review article just published in Science Translational Medicine, a set of thought-leaders including Stanford immunologist Jorg Goronzy, MD, write:
The preventive strategies (vaccines) that are currently... effective in controlling many infectious diseases may not be suited for treating the elderly population because the aged immune system does not react with the same rules as that of a younger adult.
Scientists have been leaning in to learn how those rules work. The review article summarizes factors underlying waning immune responsiveness with advancing age, strategies for restoring that responsiveness, and specific diseases for which upping vaccine potency and usage rates among older people make sense.
Our immune response declines slowly but surely starting at around age 40, Goronzy told me in an interview last year. “While 90 percent of young adults respond to most vaccines, after age 60 that response rate is down to around 40-45 percent. With some vaccines, it’s as low as 20 percent." But he and his colleagues have shown that blocking the action of a single protein found in a particular class of white blood cells may halt typical age-related declines in immune responsiveness.
It's going to be a while before exciting findings such as this translate into radical enhancements of aging people's ability to combat infection. What to do in the meantime?
First, keep moving. As the review article's authors write, "Physical exercise is strongly recommended. It has been demonstrated that moderate physical exercise greatly improves the immune reactions of elderly people."
Second, eat right - but don't starve yourself. We're told by public-health authorities that the ideal ratio of weight to height (calculated via a formula called body-mass index, or BMI) is between 20 and 25. But that's open to some question, as some studies (including this recent one conducted by the Centers for Disease Control and Prevention) suggest that the ideal ratio, from a health standpoint if not from a fashion perspective, might be a little higher. As for seniors and infection, the STM review article sides with the latter position: "The risk of death from infectious disease in people over 70 years of age has been calculated to be minimal with a BMI of 25 to 30."
Previously: Age-related drop in immune responsiveness may be reversible, Aging stem cells have clinical implications, say Stanford researchers and Exercise may protect aging brain from memory loss following infection, injury
Photo by familymwr
