Researchers propose 'immunofitness' as a measurable target for healthy aging, emphasizing vaccination's capacity to rebuild immune resilience despite age-related deterioration. Beyond pathogen-specific protection, vaccines trigger trained immunity—reprogramming innate immune cells to respond more robustly to diverse threats. Clinical evidence demonstrates that influenza, pneumococcal, COVID-19, RSV, and zoster vaccines reduce not just target infections but also cardiovascular events and all-cause mortality in older adults. This broader protective effect suggests vaccines function as immune system rehabilitators rather than merely preventive tools. The concept reframes aging immunity from inevitable decline to manageable optimization. Current vaccination approaches treat all seniors uniformly, but emerging precision vaccinology could customize schedules based on individual immune age, frailty scores, and comorbidity profiles. This personalized approach acknowledges that biological aging varies dramatically among chronological peers. The immunofitness framework offers practicing clinicians a concrete goal beyond disease prevention—actively strengthening the aging immune system through strategic immunization. Combined with lifestyle interventions, tailored vaccination represents a practical, evidence-based strategy to extend healthspan by maintaining immune competence well into advanced age.