Last Wednesday, elderly immune systems got a huge boost from an unlikely source. The Advisory Committee on Immunization Practices (ACIP), which advises the Centers for Disease Control and Prevention (CDC), recommended moving forward with Shingrix, a shingles vaccine.
What’s remarkable about Shingrix is that it dramatically eases the pain and nervous system damage associated with shingles but seems to enhance the immune systems of the elderly.
Shingles occurs when chickenpox virus, which thrives silently in the nervous system after the initial infection, reawakens after hibernation and travels down a nerve root. The result is a rash that appears as a long, thin strip along the side of the body. Sometimes shingles causes a rash on the face; when it involves the eye, shingles can cause blindness. Every year in the United States about 1 million people develop shingles. During their lifetimes, 1 of every 3 people will suffer this disease, most after they are 60 years old.
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In addition to weakened muscles, graying hair, and thinning skin, the human immune system also gets weaker and more vulnerable with age. That makes shingles especially painful and terrible for the elderly. The trademark rash, which usually resolves in about two weeks, isn’t even the worst symptom of shingles. About 90% of the time, the rash is preceded by a sharp, unrelenting, burning pain. Sometimes the pain lasts well after the rash has disappeared, for weeks and even months. This particular type of pain is called post-herpetic neuralgia, or PHN. Between 15% and 20% of people with shingles suffer PHN. Along with corneal abrasions, lower back pain, kidney stones, and labor and delivery, PHN is ranked the worst pains in medicine—so bad that it can lead to suicide.
In 2006, the Food and Drug Administration (FDA) licensed the first vaccine to prevent shingles. Called Zostavax, it contains a live, highly attenuated form of the chickenpox virus. At the time of licensure, Zostavax was recommended for all adults older than 60.
Zostavax is good but not great. It’s 51% effective at preventing the shingles rash and 67% effective at preventing PHN. Vaccine effectiveness is progressively worse in older people, the ones who need it the most. For people 60 to 69 years of age, 64% are protected against the rash; for those 70 to 79 years of age, the rate falls to 41%; and for those 80 years of age and older, Zostavax’s efficacy decreases to just 18%. Vaccine effectiveness wanes dramatically over time; four years after immunization, Zostavax’s protection against the rash drops from 64% to just 20%.
Which makes Shingrix all the more powerful in its promise. Only the second shingles vaccine to be licensed by the FDA after Zostavax, it’s much improved in efficacy and duration for the elderly. Shingrix is made using only one of the proteins contained in the chickenpox virus. Called glycoprotein E, it sits on the surface of the virus.
Shingrix’s protection rates are unprecedented in the world of immunizations—especially among the elderly. For those 50 to 59 years of age, 96.8% are protected; for those 60 to 69 years of age, it’s 97.4%, for those older than 70 to 79 years of age, it’s 97.9%; and for those older than 80 years of age, it’s 97.6%. From a medical perspective, it’s hard to find a medical product that works this well in people this age.
Typically, the best way to induce an immune response against a particular virus is to be naturally infected. Assuming that you survive the infection—and that you can tolerate the occasional severe, permanent aftereffects—immunity is often complete and long lasting. The second best way is to be immunized with a live, weakened form of the virus (like Zostavax). The third best way is to use just one part of the virus (called subunit vaccines, this was the strategy employed by Shingrix). Because they aren’t as good as live, weakened viral vaccines, subunit vaccines invariably require adjuvants to help boost immunity. So why was Shingrix better than Zostavax? The answer lies in an adjuvant that has never been used in the United States until now.
It’s called QS-21. The “QS” stands for Quillaja saponaria. Otherwise known as the soap bark tree, Quillaja saponaria is native to the country of Chile. Using a highly purified product derived from the tree’s bark (the 21st chromatographic peak in the purification process), researchers have now been able to do something that had once been considered impossible; dramatically boost a senescent (and therefore less robust) immune system. QS-21 is currently being studied for its capacity to enhance immune responses against influenza, malaria, hepatitis B virus, human papillomavirus, HIV, and tuberculosis vaccines as well as immunological strategies against lung cancer and malignant melanoma (10.4172/2329-6836.1000e113).
With the licensure of QS-21, an important door has been opened. For older adults, who are often the most vulnerable to severe and occasionally fatal infections, this kind of immune-boosting strategy will be a godsend.
The stats speak for themselves. Shingrix is phenomenal in its ability to protect against PHN. For those 50 to 59 years of age, 91.2% are protected; for those 60 to 69 years of age, it’s 89.4%; for those 70 to 79 years of age, it’s 93%; and for those older than 80, the rate is an impressive 71.2%. Protection afforded by Shingrix also lasts longer. Overall protection against shingles rash was 97.6% after one year, 92% after 2 years, 87.9% after 3 years, and 84.7% after 4 years.
That doesn’t mean Shingrix is a perfect vaccine. It comes with a host of side effects: local pain, redness, achiness, fatigue, fever, and swelling occur in the two days after the vaccine shot. Ninety-five percent of people who experienced these side effects, though, reported it didn't interfere with their quality of life.
What does Shingrix show us? For one thing, the future of vaccines might lie in adjuvants. There’s also the added benefit of the seemingly impossible: improving the immune system against this virus as a person ages. Whether or not that fundamentally affects the treatment and experience of the elderly in other diseases remains to be seen, but it’s a huge first step.
