The influenza vaccine does not confer equal protection to everyone. Latest data shows that individuals who experience “immunosenescence” (immune aging), particularly those aged 80 and over, as well as those taking immunosuppressants or suffering from severe obesity, may not achieve the expected antibody levels from standard vaccines, leading to a significant drop in preventative effectiveness.
As of 2025, the reason people feel the vaccine “doesn’t work” is often the combination of “Ages 80+ + Standard Vaccine.”
2025 Ranking of “People Who Respond Poorly to the Flu Vaccine” (Based on Actual Data)
| Rank | Who are They? | Degree of Reduced Effectiveness | Reason / Actual Data |
| 1st | Ages 80+, especially 85+ | ★★★★★ (Effectiveness drops to 30% or less for some) | Immunosenescence (Immune aging) means antibody levels barely rise. |
| 2nd | Frail, bedridden seniors residing in facilities | ★★★★★ | Malnutrition + lack of exercise results in almost zero immune response. |
| 3rd | Taking ≥20mg/day of steroids, undergoing chemotherapy, or post-transplant | ★★★★★ | Immunosuppression reduces antibodies to less than one-tenth. |
| 4th | Severe obesity (BMI≥40) | ★★★★☆ | Chronic inflammation confuses the immune system (30–50% reduction in effect). |
| 5th | Vaccinated every year (5+ consecutive years) | ★★★☆☆ | Antibody levels plateau due to the “negative imprinting” phenomenon. |
| 6th | Poorly controlled diabetes (HbA1c≥8.5) | ★★★☆☆ | High blood sugar prevents immune cells from working (20–40% reduction in effect). |
| 7th | Ages 75–79 | ★★☆☆☆ | Effectiveness drops to about half with the standard vaccine. |
| 8th | Extreme drinkers (2+ cups of sake/day) | ★★☆☆☆ | Liver burden + reduced immunity causes a 10–30% drop in effectiveness. |
2025 “Strongest Countermeasures for Poor Responders”
| Your Type | Vaccine to Get | Additional Action to Take |
| Ages 80+, Facility Residents | Fluad (High-Dose) is the only choice | Gives 1.5 to 2 times the effect of the standard vaccine. |
| Taking Immunosuppressants/Chemotherapy | Consult with a doctor (Fluad if possible) | Ensure all family members are vaccinated (Indirect protection). |
| Severe Obesity (BMI≥40) | Fluad or Recombinant Vaccine | Effectiveness dramatically restored by losing 5kg of weight. |
| Vaccinated Every Year but Still Get Sick | Switch to the Recombinant Vaccine this year | New antigens help antibodies re-surge. |
| Poorly Controlled Diabetes | Fluad | Effectiveness almost fully restored by achieving HbA1c≤7.0. |
Summary
People for whom the vaccine “doesn’t work” are usually in the category of: → Ages 80+ + Standard Vaccine → Immunosuppression + Standard Vaccine
Any other scenario can be virtually resolved simply by “switching to Fluad or the Recombinant Vaccine!” (Especially for those aged 80+, there are numerous cases where switching to Fluad immediately stopped the cycle of getting the flu every year.)
Influenza vaccines do not confer equal protection to everyone. Latest data shows that individuals who experience “immunosenescence” (immune aging), particularly those aged 80 and over, as well as those taking immunosuppressants or suffering from severe obesity, may not achieve the expected antibody levels from standard vaccines, leading to a significant drop in preventative effectiveness.
As of 2025, the reason people feel the vaccine “doesn’t work” is often the combination of “Ages 80+ + Standard Vaccine.”
