I'm getting two vaccines next week: Tdap and shingles. The Tdap because Kate's family has a newborn and we're visiting. Shingles for the potential longevity benefits. Data we're looking at: 1. Lower Alzheimer risk with vaccination in 1.6 million people, 8 year follow up, age 65+ + Tdap/Td: 30% lower relative risk + Shingles: 25% lower + Pneumococcal: 27% lower 2. Slower biological aging from shingles vaccination in 3,884 people, age 70+ Modest but significant improvements in inflammation, epigenetic and transcriptomic aging, and composite biological age. Molecular signals strongest within 3 years; inflammation benefits emerged later. 3. Better outcomes after breakthrough shingles in 38,092 people, age 50+, median 3.6y follow up In adults who developed shingles, prior vaccination was linked to: + 41% lower all-cause mortality + 21% lower MACE (MI, stroke, PE, sudden cardiac death) + 16% lower dementia risk Note: all three studies are observational. They show association, not causation. A randomized controlled trial on longevity outcomes is not feasible here as you can't randomize people to skip vaccines for years. The signal is consistent across independent large cohorts, which strengthens confidence, but the possibility of healthy vaccine bias exists in all three. People who stay current on vaccines tend to have better health behaviors overall. I find the mechanistic case for shingles specifically compelling. VZV reactivation drives neuro inflammation, and vaccination appears to blunt that cascade which is why we weight this evidence more heavily than the numbers alone.