A patient sat across from me not long ago and told me she wasn’t sure she could trust vaccines anymore. Lots of things surprised me about living through COVID, but probably the one with the longest tail is how my friends, family and patients think about vaccines. They are large, replicated and increasingly mechanistic: Investigators now suspect the vaccine’s adjuvant itself trains the immune system in ways that ripple far beyond the shingles (and chicken pox) causing varicella-zoster virus. The immune system, as it turns out, learns more broadly than we taught it to. The American Heart Association recommends several vaccines, including flu, pneumovax, shingles and COVID-19, as part of cardiovascular care due to their ability to lower risk of heart disease.