Real protection
Vaccines reduce the risk of infection, severe disease and complications.
Vaccination
Training Your Immune System
for a Healthier Tomorrow
Vaccines safely teach your immune system to recognize and fight pathogens before they can make you sick. They have transformed global health, saved millions of lives, and remain one of the most effective tools for healthy aging.
Explore how vaccines workToday’s
vaccines.
Healthier
tomorrows.
vaccines.
Healthier
tomorrows.
A healthier society
High vaccination rates protect families and communities.
Healthy aging
Vaccination helps maintain immune health and independence later in life.
What Is a Vaccine?
A vaccine is a safe way to expose your immune system to a harmless piece of a pathogen, or instructions to make that piece, so your body can learn to recognize and fight the real pathogen in the future.
Same target
as the real pathogen
Triggers a protective
immune response
Designed to prevent
the disease
How Vaccines Work
A step-by-step guide from exposure to long-term protection.
1. Antigen exposure
Vaccines provide antigens or instructions; live vaccines require care in immunocompromised people.
2. Antigen presentation
Dendritic cells capture the antigen and activate T cells in lymph nodes.
3. T and B cell activation
Helper T cells activate B cells and cytotoxic T cells.
4. Antibodies and immune memory
B cells produce antibodies; memory B and T cells provide long-term protection.
Types of Vaccines
Different technologies, same goal: a stronger, smarter immune system.
Live attenuated vaccines
- Weakened form of a virus or bacterium
- Strong, long-lasting immunity
- Examples: MMR, varicella, yellow fever
Inactivated vaccines
- Killed virus or bacteria
- Cannot replicate
- Well-established technology
- Examples: polio (IPV), hepatitis A, influenza (some)
Subunit / protein vaccines
- Specific pieces of a pathogen (e.g., proteins)
- Cannot replicate
- Often combined with an adjuvant
- Examples: hepatitis B, HPV, recombinant shingles
Toxoid vaccines
- Inactivated toxins produced by bacteria
- Stimulate antitoxin immunity
- Examples: tetanus, diphtheria
Viral vector vaccines
- Harmless virus delivers genetic instructions
- Induces strong immune responses
- Examples: Johnson & Johnson COVID-19, some Ebola vaccines
mRNA vaccines
- mRNA provides instructions for your cells to make a protein
- Does not enter the nucleus or alter DNA
- Rapidly developed and highly effective
- Examples: COVID-19 vaccines; next-generation vaccines
Vaccines Across the Lifespan
Vaccines play an important role at every stage of life.
Infancy
Build early protection (e.g., DTaP, polio, Hib, pneumococcal, rotavirus)
Childhood
Maintain protection (e.g., MMR, varicella, HPV later in childhood)
Adolescence
Prepare for new risks (e.g., HPV, meningococcal)
Adulthood
Stay protected (e.g., influenza, COVID-19, hepatitis)
Older Adults
Extra protection is critical (e.g., influenza, COVID-19, RSV, shingles, pneumococcal)
Different life stages. Different risks. Lifelong benefits.
Vaccination and Healthy Aging
As we age, the immune system changes — but vaccines still work.
- Older adults are at higher risk of severe disease from infections such as influenza, COVID-19, pneumonia, RSV and shingles.
- Immune responses may be weaker, but adapted vaccines (e.g., higher dose or adjuvanted) can improve protection.
- Vaccination helps preserve independence, quality of life and healthy aging.
Are Vaccines Safe?
Vaccines are among the most studied medical interventions in history.
Common Side Effects
Usually mild and short-lived.
Soreness
at injection site
Mild fever
Tiredness
Headache
These reactions can occur as the immune system responds.
Selected sources and references
- CDC — Explaining how vaccines work
- CDC — Vaccines by age
- Immunosenescence and human vaccine immune responses, 2019
Artwork illustrates the main mechanisms schematically; molecular sizes, colors and distances are not literal.