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  • Writer's pictureP.K. Peterson

Protecting Older Adults from Serious Infections

Vaccines are the tugboats of preventative health.

- William Foege, MD, MPH, American physician and epidemiologist

“Walking is man’s best medicine.”

- Hippocrates, 480 BCE, Greek physician and founder of Western medicine

If I had to pick one factor that plays the most powerful role in determining the seriousness of an infection it would be advanced age. As we age, the potency of our immune system wanes (termed immunosenescence) and along with it, our ability to fight infectious agents diminishes. When coupled with age-related comorbidities like cardiovascular and pulmonary disease, this biological phenomenon is the basis for the increased risk of serious outcomes of infections in older adults. In today’s Germ Gems post, I focus on the infectious diseases that pose the biggest threat to the health of older adults and what can be done to protect against them.

Who is considered an “older person”? The chronological definition of “elderly,” that is anyone greater or equal to 65 years-of-age, is often used to characterize someone as “old.” The American Psychological Association (APA), however, states that the term “elderly” is considered by some a pejorative adjective and not acceptable as a noun. The APA prefers the term “older person.” As an older person, so do I.

As everyone knows, the chronological age cut off (age 65 or greater) doesn’t necessarily reflect the physiological age of a person. In my June 7, 2023 Germ Gems post, “Shingles: The Chickenpox Virus’s Second Act,” I noted that the Center for Disease Control and Prevention (CDC) recommends that anyone 50 years-of-age or older receive Shingrix vaccine to prevent reactivation of the chickenpox virus (varicella virus [VZV]). Lacking good biomarkers of physiological age, I’ve come to accept “50 years-of-age” as the arbitrary definition of an “older adult” when discussing infectious diseases.

Vaccine preventable infections. Vaccines prevent many infectious diseases, and older adults often benefit the most from vaccines. Below, I summarize the CDC’s and World Health Organization’s (WHO) vaccination guidelines for older adults. You should, however, always confer with your primary care provider for their input (and when indicated, for a prescription).

Shingles (herpes zoster) Shingles can be very serious in older adults. (See, June 7, 2023 Germ Gems post). The shingles vaccine (Shingrix) cuts the risk of shingles in adults 50 years and older by more than 90%.

At about the same time that my June Germ Gems was posted, a publication in Nature News, “Does shingles vaccination cut dementia risk? Large study hints at a link,” reported that a recent study in Wales suggested the shingles jab also is associated with a 20% lower risk of developing Alzheimer’s disease. Prior to the Welsh study, other studies implicated VZV in the pathogenesis of Alzheimer’s disease. So let’s hope still other research groups verify the findings of the Welsh investigators which would certainly drive up interest in the Shingrix vaccine.

COVID-19 From the beginning of the SARS-CoV-2 pandemic, older adults bore the brunt of more serious infections, resulting in increased hospitalizations, admissions to intensive care units, and deaths. Overall, people in America aged 65 and older accounted for 75% of deaths; in 2023 their share of the death toll rose to 90%. As New York Times journalist, David Wallace-Wells put it, “It’s much harder to train older immune systems, and that training diminishes more quickly.”

The mRNA COVID-19 vaccines work well in older adults, reducing the mortality risk about eightfold and also protecting against long Covid. Moreover, the bivalent booster, which targets both the original coronavirus strain as well as two omicron subvariants (BA.4 and BA.5) provided substantial protection against death in older adults for up to six months.

The COVID-19 pandemic is not over, especially for older adults. Moving forward, both the CDC’s and WHO’s vaccine strategy now is for older adults to receive an updated booster that is specific to just one omicron variant, XBB.1.5.

If you are an older adult and are up-to-date on your vaccine status, that is, you’ve had two bivalent boosters, the CDC and WHO recommend that you sign up for the XBB.1.5 booster once it’s available this fall. Anyone who is unsure about their vaccine status should speak with their primary care provider about what’s needed. (And if you’ve missed getting the Shingrix vaccine, talk to your provider. You may safely get both vaccines (i.e., for protection against VZV and SARS-CoV-2) at the same visit.

The medical armamentarium to prevent serious COVID-19 infections in older adults includes medications as well as vaccines. While some agents have fallen by the wayside, several pharmacological agents, such as Paxlovid (nirmatrelvir/ritinovir) and remdesivir, remain potentially valuable treatments. And promising new agents, like pegylated interferon, are in the treatment pipeline.

If you become ill with COVID-19 (rapid diagnostic testing for SARS-CoV-2 is still available), consult your primary care provider about treatment with Paxlovid (they’ll know about your eligibility and any potential drug-drug interactions). The reason I personally favor Paxlovid is that it’s been shown to prevent long COVID, a serious complication of SARS-CoV-2 infection that older adults are at increased risk of developing. (It is estimated that as many as 16 million Americans currently suffer from long COVID-19.)

Influenza Older adults are at greatest risk of developing severe and fatal influenza. (For a detailed discussion, I recommend the May 7, 2023 Open Forum Infectious Diseases article, “Age differences in comorbidities and outcomes of influenza illness requiring hospitalization: a worldwide perspective from the Global Influenza Hospital Surveillance Network.”) The CDC continues to recommend annual flu shots as the mainstay of prevention of the flu. It will soon announce to providers what influenza strains are targeted in this year’s vaccine before the flu season begins in the fall.

Unfortunately, seasonal flu vaccines are oftentimes not all that effective. For example, researchers reported recently that the 2022 flu vaccine didn’t provide protection in adults 65 years of age and older (See March 15, 2023 Clinical Infectious Disease “Vaccine Effectiveness Against Influenza A(H3N2)-Associated Hospitalized Illness: United States, 2022.”). Thus, we need a new approach to flu vaccine for older adults.

Many public health experts were pulling for development of a new mRNA flu vaccine. They were disappointed, however, by the news that the pharmaceutical company Sanofi is “back to the drawing board” on its mRNA flu vaccine following disappointing results of early-stage testing.

On the influenza treatment front, controversy around the popular antiviral drug Tamiflu has led some doctors to prescribe the single-dose alternative Xofluza. If you get the flu this year, confer with your primary care provider about treatment. (Rapid tests for the diagnosis of all of the “Big 3” viruses—SARS-CoV-2, influenza virus, and respiratory syncytial virus [RSV]—are available without needing a provider visit. Check with your local state health department regarding where you can get this rapid multi-virus diagnostic test.)

RSV There is exciting news for older adults in the prevention of RSV. As I discussed in my October 5, 2022, Germ Gems post, “Respiratory Syncytial Virus: A Little Known Virus with a Big Impact,” RSV is a major threat to older adults. In fact, a publication this June in Clinical Infectious Diseases, “Prevalence and Clinical Outcomes of Respiratory Syncytial Virus vs Influenza in Adults Hospitalized with Acute Respiratory Illness From a Prospective Multicenter Study,” shows that RSV is not only a very prevalent respiratory tract infection, but it is associated with worse outcomes than influenza.

Given this background of the seriousness of RSV, older adults should celebrate GSK’s and Pfizer’s development of the first Federal Drug Administration-approved, protein-based RSV vaccines. On June 29, 2023, the CDC recommended the vaccines for some older adults. The Advisory Committee on Immunization Practices said that adults 60 and older may receive one dose of the vaccine after discussions with their health provider. I strongly endorse these recommendations and this fall hope to receive my RSV jab along with the new COVID-19 booster and also the flu vaccine.

Pneumococcal vaccination In addition to the very nasty “Big 3” viruses that plague older adults, the bacterium Streptococcus pneumoniae (commonly referred to as pneumococcus) is a major threat to older adults. Globally, S. pneumoniae is the leading cause of pneumonia mortality. In the U.S., about 150,000 people are hospitalized with pneumococcal pneumonia per year, and the mortality of older adults with pneumococcal pneumonia is about 20%. In addition to pneumonia, the pneumococcus is a leading killer of patients with bacterial meningitis, plus it is a major cause of otitis media and sinusitis.

Like the “Big 3” viral causes of respiratory tract infections, S. pneumoniae infections are vaccine preventable. Because of its role in pneumonia, the pneumococcal vaccine is often referred to as the “pneumonia shot.” But this vaccine also prevents the other pneumococcal infections I’ve mentioned.

In April of this year, the CDC recommended that older adults receive what is called the “higher valent” pneumococcal conjugate vaccine. It is called “higher valent” or “multivalent” because it targets 15 different strains of S. pneumoniae. Whether or not you were jabbed previously with a lower valent pneumococcal vaccine, your primary care provider can tell you when and what you may need in the way of the “pneumonia shot.”

Nonpharmacological intervention to reduce the risk of serious infections. The idea that exercise promotes human health isn’t new. None other than the founder of Western medicine, Hippocrates, suggested “[w]alking is man’s best medicine.”

There is now mounting evidence that regular exercise has beneficial effects on the immune system, thereby helping to prevent the serious consequences of infectious diseases. In a January 10, 2023, WebMD Health News article, “Are Your Patients Using This Anti-COVID Secret Weapon,” journalist Lisa Jhung cites research from Kaiser Permanente suggesting that exercise in almost any amount can cut the risk of severe or fatal COVID-19 among high-risk patients.

Reflecting the value of exercise in promoting human health, the CDC’s “Physical Activity Guidelines for Americans” recommends that adults get at least 150 minutes of moderate-intensity aerobic physical activity per week. (For example, 30 minutes of brisk walking 5 days a week.)

Walking rather than driving is also good for the climate. So for your physical and mental health, as well as the health of the environment, take it from Hippocrates and get serious about walking.

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Main Page images courtesy of Shuxian Hu, MD. Dr. Hu is a scientist in the Neuroimmunology Research Laboratory at the University of Minnesota.

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