Hi Reader,

Welcome to the refreshed format of The Longevity Letter.

My goal for 2026 is simple: High signal, low noise. You are busy, and the longevity space is getting louder, not clearer. I’ve redesigned this newsletter to be your weekly "Insider’s Rounds"—a briefing on what matters, what works, and what I’m personally testing.

We are moving from general advice to specific, actionable intelligence.

The TL;DR if you only have 30 seconds:

• 👻 The Deep Dive: Why I’m treating the Shingles vaccine as an anti-aging drug (and the concept of the "Viral Ghost").
• 💊 The Protocol: My personal battle with post-COVID immunosenescence, and why Low Dose Naltrexone (LDN) was a game-changer for me.
• 📉 The Chart: The "Shingrix Gap"—how one vaccine bought patients 17% more dementia-free time.
• ⚡ Quick Hits: NVIDIA’s robot labs, Stanford’s sleep predictions, and the T-cell breakthrough.

Let's get into it.

🩸 The Deep Dive: The "Ghost War" in Your Blood

If you think of the Shingles vaccine simply as "rash prevention," you are missing the bigger picture. Yes, it prevents a painful outbreak in anyone with a history of Chickenpox (I’ve had Shingles twice—I know the misery).

But new data from USC (published this week, Jan 20) suggests the Shingrix vaccine might be one of the most powerful anti-aging interventions we have.

The Biological Age News:

It’s Not Just About the Rash. Researchers found that recipients of the Shingles vaccine showed slower biological aging (measured by epigenetic clocks) compared to the unvaccinated. This data adds the "biological why" to the massive 2024 Nature Medicine study, which found that recipients of the recombinant vaccine (Shingrix) gained 17% more diagnosis-free time compared to those who received the old live vaccine.

• The Impact: That’s 164 extra days of healthy life gained in just a 6-year window. (A separate study has placed the absolute risk reduction closer to 20%).
• Crucial Detail: This protection wasn’t just against Alzheimer’s, but likely extending to Vascular Dementia as well. Why? Because the same inflammation that rots neurons also stiffens blood vessels.
• Bonus: Another study has shown Shingles vaccination to be associated with up to 18% lower risk of heart attack and stroke.

Why is a vaccine slowing down aging?

It comes down to Immunosenescence (the aging of the immune system).

Most of us carry a "Ghost Burden" of latent pathogens that never truly leave the body. They sleep in our nerve roots or tissues, waiting for a moment of weakness to reactivate.

• The Usual Suspects (Viruses): Varicella (Chickenpox), CMV (Cytomegalovirus), HSV (Herpes Simplex), and EBV (Mono). These affect about 95% of the population, so they're definitely not rare!
• The Other Invaders (Bacteria): It’s not just viruses. P. gingivalis (the gum disease bacterium) and H. pylori (GI ulcer bacteria) act similarly. They create a low-grade, chronic "leak" of toxins into the bloodstream, resulting in inflammation.

The Cost: The "Immune Tax" As we age, our immune system weakens, and these ghosts try to wake up. Your body is forced to deploy massive resources just to keep them dormant.

• The Drain: By age 70, a massive portion of your T-cells (sometimes up to 50% in the case of CMV) are exhausted solely from fighting this silent, invisible war.
• The Damage: This constant battle creates "inflammaging"—systemic inflammation that damages the endothelial lining of your heart and the blood-brain barrier.
• The Result: Your immune system becomes so distracted fighting the "Ghosts" that it misses the new threats (like cancer cells or amyloid plaques in dementia).

The "Insider" Protocol

I now view Shingrix not as "pathogen avoidance" but as "Immune Energy Conservation."By training the immune system to effortlessly suppress Varicella, you stop the "leak" of inflammation. You free up metabolic resources for repair, rather than defense.

The Takeaway:

• Get the Shot: If you are 50+, get Shingrix. You are buying your immune system some breathing room.
• Fight the Bacteria: Since we don't have vaccines for conditions like P. gingivalis yet, your dental hygiene is actually a longevity intervention. Flossing isn't for your teeth; it's to stop oral bacteria from leaking into your brain (where they have been found in Alzheimer's autopsies).
• Watch the Stress: High cortisol wakes up these viruses. Stress management is viral containment.

(Insider Thought: Given that this "Ghost War" starts decades earlier, I am closely watching for data on whether we should be vaccinating people in their 30s and 40s to prevent this immune exhaustion before it starts.)

🧪 The CEO’s Protocol: The Mystery of Low-Dose Naltrexone

I wrote the "Ghost War" Deep Dive not only because this news is truly interesting from a longevity perspective, but also because I’ve lived it.

Last year, I recovered from an acute bout of COVID (my third time, and the worst round). I eventually stopped having acute symptoms, but I didn't feel recovered. I had nervous system symptoms affecting everything from my mood to sleep to fitness and recovery.

When I finally got epigenetic testing, my biomarkers showed I was fighting a hidden battle:

• The Smoking Gun: My CD4/CD8 Ratio had plummeted to the 9th percentile.
• The Translation: A low ratio means your "Killer" cells (CD8) have expanded aggressively, likely to fight a latent threat, while your "Helper" cells (CD4) are depleted. This is the biological signature of Immunosenescence—my immune system looked decades older than I am.
• The Fuel: My Chronic Stress Marker (Kynurenine) was in the 84th percentile (High Risk). High cortisol was suppressing my immune system, allowing these "Viral Ghosts" to drain my energy.

The Realization: It wasn't that the virus was actively replicating; it was that my immune system was stuck in a "maladaptive alarm" state. Specifically, my glial cells (the immune cells of the brain) were hyper-active, fighting a ghost that wasn't there. This is the exact same mechanism that makes latent viruses like CMV and EBV so aging—the chronic inflammation burns through your T-cell reserves.

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The Intervention: Low Dose Naltrexone (LDN) Since I couldn't just "rest" my way out of this, I needed to modulate the alarm. I started a protocol of LDN (<4.5mg at night).

• The Mechanism (The "Aha"): At 50mg, Naltrexone blocks opioids and is used for treating conditions like alcohol or opioid dependency.
• But at tiny doses like 4.5mg, it acts as a TLR4 Antagonist on glial cells (the brain's immune system). It effectively tells the brain to "stand down" and stop pumping out inflammatory cytokines (like IL-6).
• The Result: For me, the effect was profound. My sleep improved, my mood normalized, and my recovery metrics (HRV) literally doubled.

Other Tools for the "Ghost War" We can't vaccinate against every pathogen (including non-viral ones like P. gingivalis), so here are other ways to tackle immunosenescence:

1. Thymic Support: The thymus (where T-cells are made) turns to fat as we age. I am closely tracking the literature on Thymosin Alpha-1 peptides to reverse this atrophy. (Note: while TA1 is used in other countries, the FDA has not yet approved it for use in the U.S.)
2. Oral Defense: Since bacteria like P. gingivalis (gum disease) can leak into the brain and drive dementia, I treat flossing as a longevity intervention, not just hygiene.
3. Cortisol Management: My report proved that stress was fueling my viral load. Cortisol management isn't just "wellness"—it is viral containment.

(Disclaimer: I am a doctor, but I am not your doctor. LDN is a prescription medication. Do not start this without medical supervision.)

⚡ Longevity Quick Hits

💊 The “Ageless” Cocktail Trial Begins - Monotherapies are out; combos are in. A new clinical trial is recruiting healthy older adults to test Rapamycin (mTOR inhibitor) combined with Lamivudine (an HIV drug that targets “jumping genes”). The goal? To see if hitting two hallmarks of aging simultaneously—nutrient sensing and genomic instability—outperforms either drug alone.

🐩 FDA Clears Safety Step for Dog Longevity - The regulatory path for lifespan extension is officially open. The FDA just cleared the safety data for Loyal’s LOY-002, a drug designed to extend the lifespan of senior dogs. While it’s for canines, this is a massive precedent: the FDA is accepting “lifespan” as a valid drug endpoint, paving the way for human equivalents.

🥗 “Nutrition as Medicine” Gets a $36M Boost - The longevity diet is going clinical. L-Nutra (makers of ProLon) just secured a $36.5M Series D extension to validate their fasting-mimicking diets as insurance-reimbursable treatments for diabetes and cardiovascular disease. This signals a major shift from “wellness lifestyle” to “prescribed intervention.”

🤖 AI’s “Hidden” Bias Problem A wake-up call for digital health: A new study from Northeastern University reveals that medical LLMs act like detectives with bad habits—they infer a patient's race even when it’s explicitely stripped from the data, subtly altering treatment plans (like suggesting lower pain meds). This proves that “blind” data isn't enough to fix systemic bias. The algorithm is watching, and it’s judging.

⚖️ The GLP-1 Rebound is Real We knew it was coming, but now we have the number. A massive new analysis confirms that the cardiovascular and metabolic benefits of GLP-1s (like Ozempic/Mounjaro) effectively vanish within 1.5 years of stopping the drug. This reinforces the hard clinical truth: obesity is a chronic condition, not a short-term fix. If you start, plan for the long haul—it’s a life-long subscription, not a cure.

2026 is About Focus

With all that's happening in longevity and AI recently, it can feel chaotic. I have made a commitment to be focused this year to bring the best information and solutions to you all as my audience. (I've already declined four conference opportunities for Q1! Down from the 6 I attended just for Q4.)

In the upcoming weeks, I'll be sharing not only the usual news but also some exciting opportunities to be one of the very first users of CareCore. If you are someone who's been wanting to get started on a longevity medical program (GLP-1 for weight loss, microdose, NAD+, glutathione, or sermorelin), or you're a clinician or brand who wants to offer this to your audience, please reply and let me know your interest!

'Till next week,

Hillary Lin, MD

Co-Founder & CEO

​Care Core​

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Follow me for more longevity insights: YouTube | LinkedIn | Instagram | TikTok​

Want to turn your wellness brand into a full-service health destination? Learn about Care Core's platform or Get Started Here​

Where to find me:

Physician Creator Trends – VSP Innovation Center & Matter Fireside Chat (Virtual) – Jan 28 @ 1PM EST link here. So excited about this topic!

👱🏻‍♀️👩🏻‍🦰👩🏻👧🏽👧🏾 Livelong Women’s Health Summit – April 17-18, 2026, SF, CA. Delighted to join 50 other thought leaders in speaking on women's longevity!​

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