Why is Shingrix only for over 50? Understanding vaccine efficacy and risk factors

While the varicella-zoster virus that causes shingles lies dormant in nearly all adults over 50, the risk of it reactivating increases significantly with age as the immune system weakens. This age-related decline is the primary reason why is Shingrix only for over 50 and not recommended for the general younger population.

Quick Summary

The vaccine is targeted at older adults because their natural immunity declines, increasing their risk of shingles and severe complications like postherpetic neuralgia. Efficacy data from clinical trials in this age group secured FDA approval. Younger, healthy individuals maintain robust immunity, making vaccination unnecessary, though exceptions exist for those with weakened immune systems.

Key Points

• Immune System Decline: The risk for shingles significantly increases after age 50 due to the natural weakening of the immune system, a process known as immunosenescence.

• FDA Approval and Clinical Trials: The FDA approved Shingrix for adults 50 and older based on clinical trials (ZOE-50 and ZOE-70) that demonstrated high efficacy and safety in this age group.

• High Efficacy: Shingrix is proven to be over 90% effective in preventing shingles and postherpetic neuralgia in adults aged 50 and older with healthy immune systems.

• Targeted Public Health Strategy: Focusing vaccination on the highest-risk group (50+) is a cost-effective public health strategy, as the risk in healthy younger adults is much lower.

• Exception for Younger Immunocompromised Adults: Shingrix is also recommended for immunocompromised adults aged 19 and older, as their condition puts them at a high risk for shingles regardless of age.

• Boosted, Durable Protection: The vaccine's formulation includes an adjuvant that helps overcome the age-related decline in immune response, providing robust and long-lasting protection.

• Not Tested for Healthy Younger Population: The vaccine's efficacy and safety were not specifically studied in the general, healthy younger adult population, limiting its approved indication.

The Connection Between Age and Immune Decline

Our immune system, a complex network of cells and proteins, undergoes a natural aging process known as immunosenescence. This is the central reason behind the Shingrix age restriction for healthy adults. As we get older, our immune response becomes less robust and efficient. This decline affects the body's ability to keep the varicella-zoster virus, which causes chickenpox, in a dormant state. The weakened immune system allows the virus to reactivate, travel along nerve pathways, and cause the painful, blistering rash of shingles.

Clinical data show a sharp increase in the incidence and severity of shingles starting around age 50. The vaccine was specifically developed to address this age-related vulnerability. For younger, healthy individuals, a strong immune system effectively suppresses the dormant virus, making the vaccine largely unnecessary and less cost-effective for mass vaccination.

Clinical Trials and FDA Approval

GlaxoSmithKline's development of Shingrix involved extensive phase 3 clinical trials, including the ZOE-50 and ZOE-70 studies. These trials focused on testing the vaccine's efficacy and safety in adults aged 50 and older and were crucial in securing the FDA's approval for this specific age group.

• ZOE-50 Study: Showed high efficacy against shingles in adults aged 50-69.
• ZOE-70 Study: Confirmed high efficacy in adults aged 70 and over.
• No young adult data: Testing was not mandated or pursued for the general healthy younger population due to the vaccine's focus on age-related immune decline, thus limiting the FDA approval to the studied age groups.

Comparing Shingrix for Healthy vs. Immunocompromised Adults

While the 50+ recommendation is for healthy adults, the FDA expanded the indication to include immunocompromised adults aged 19 and older due to their significantly higher risk of developing shingles at any age.

Feature	Healthy Adults 50+	Immunocompromised Adults 19+
Primary Rationale for Vaccination	Age-related decline in natural immunity.	Medical conditions or therapies that suppress the immune system.
Typical Dose Schedule	Two doses administered 2 to 6 months apart.	Two doses administered 1 to 2 months apart, depending on clinical judgment.
Efficacy	Over 90% effective in clinical trials.	Efficacy ranges from 68% to 91%, depending on the specific condition affecting the immune system.
Risk Profile	Recommended due to natural rise in shingles risk with age.	Recommended due to heightened risk of shingles and associated complications, which overrides typical age considerations.

Efficacy and Longevity

Shingrix offers superior and more durable efficacy against shingles and its complications like postherpetic neuralgia compared to the older Zostavax vaccine. Its long-lasting protection is particularly beneficial for older adults with weakened immune systems. The adjuvant in Shingrix helps boost the immune response to overcome age-related decline.

The Cost-Benefit Analysis for Public Health

Public health agencies like the CDC consider cost-effectiveness when making recommendations. Shingles risk is low in healthy individuals under 50, making mass vaccination for this group less cost-effective. Prioritizing the 50+ demographic ensures resources are used effectively to prevent cases and severe complications in the most vulnerable population.

Conclusion

In conclusion, the age 50 and over recommendation for Shingrix is based on the increased risk of shingles with age due to immune system weakening. Clinical trials confirmed high efficacy and safety in this age group, leading to FDA approval and CDC recommendations. While also approved for younger immunocompromised adults, the recommendation for healthy individuals targets the demographic with the greatest risk and potential benefit. Consult a healthcare provider to determine if Shingrix is appropriate for you.

Frequently Asked Questions

Why is the shingles vaccine not recommended for healthy people under 50?

For healthy adults under 50, the risk of developing shingles is significantly lower because their immune system is typically strong enough to keep the varicella-zoster virus dormant. The vaccine is most effective and cost-efficient when given to the high-risk population, which starts at age 50.

Can a healthy person under 50 get the Shingrix vaccine?

While the CDC doesn't recommend it for the general population under 50, an individual may be able to get the vaccine off-label with a doctor's prescription. This is often determined on a case-by-case basis and insurance coverage may vary.

What if I'm under 50 but have a weakened immune system?

For immunocompromised adults aged 19 and older, the CDC does recommend the Shingrix vaccine. This is because their weakened immune system puts them at a much higher risk of developing shingles, regardless of age.

What are the main risk factors for shingles?

Besides age, other risk factors for shingles include having a compromised immune system from certain diseases (like HIV) or medical treatments (such as chemotherapy), and experiencing high levels of stress. The decline of the immune system that comes with aging is the most common factor.

Do I need to get Shingrix if I already had shingles?

Yes, the CDC recommends getting the Shingrix vaccine even if you have had a shingles episode in the past. {Link: NCOA website https://www.ncoa.org/article/how-long-does-the-shingles-vaccine-last/}.

Is Shingrix a live vaccine like the old Zostavax vaccine?

No, Shingrix is a recombinant, non-live vaccine, unlike the older Zostavax vaccine which was live-attenuated. This makes Shingrix a safer option for many individuals, including those who are immunocompromised.

How effective is Shingrix for adults over 50?

In clinical trials, Shingrix demonstrated high efficacy, showing 97% effectiveness in preventing shingles in adults aged 50-69 and 91% effectiveness in those 70 and older. {Link: NCOA website https://www.ncoa.org/article/how-long-does-the-shingles-vaccine-last/}.

Frequently Asked Questions

What is the main reason for the age 50 recommendation for Shingrix?

The main reason is that the risk and severity of shingles increase significantly after age 50 due to the natural decline of the immune system, a process called immunosenescence. Shingrix is specifically developed and approved to protect this high-risk population.

Did the FDA approve Shingrix for adults under 50?

No, the FDA initially approved Shingrix for adults aged 50 and older based on clinical trial data focused on this demographic. The approval was later expanded to include immunocompromised individuals aged 19 and up, but not for the general healthy population under 50.

What is different about the immune system in older adults compared to younger adults?

As people age, their immune system becomes less effective at fighting infections, including keeping the varicella-zoster virus dormant. Studies show that older individuals mount a less robust immune response to vaccines compared to younger adults.

Why is Shingrix different for immunocompromised adults?

Immunocompromised adults, even if younger, are at a higher risk for shingles because their immune system is already suppressed by disease or therapy. The potential benefit of the vaccine for this high-risk group outweighs the standard age considerations, which is why it's recommended for them at age 19+.

Why isn't Shingrix tested on younger, healthy people?

Since healthy people under 50 have a much lower risk of shingles and robust natural immunity, testing for this group was not deemed a priority. The vaccine development and approval process focused on the population most in need of protection based on the epidemiology of the disease.

What if a younger person wants to get the vaccine? Can they?

A healthy person under 50 can talk to their doctor about receiving the vaccine off-label, but coverage is not guaranteed and there is less data on its long-term benefits for this group. For immunocompromised individuals 19 and older, the vaccine is formally recommended and covered.

How long does the protection from Shingrix last for older adults?

Clinical studies have shown that Shingrix provides durable protection. For adults 50 and over, it can offer high protection for a decade or more after the two-dose series is completed. {Link: NCOA website https://www.ncoa.org/article/how-long-does-the-shingles-vaccine-last/}.