Are vaccines an effective tool to prevent disease?

Vaccines are a proven disease prevention tool — I'll gather the latest evidence on how well they work.

Yes, vaccines are one of the most effective tools available to prevent disease.

Scientific evidence is clear that vaccines are highly effective and provide strong health benefits at relatively low cost:

> "continue to trust in vaccines as one of the most effective tools to prevent diseases. Put simply, vaccines provide strong health benefits at a relatively low cost to society"

1. How vaccines prevent disease

Vaccines reduce risks of getting a disease by working with your body’s natural defenses to build protection. When you get a vaccine, your immune system responds.

They are made from small, weakened or inactive pieces of a germ— such as a virus or bacteria—that cannot cause disease. Instead, they safely show the immune system what the real germ looks like. This allows the body to produce protective defenses called antibodies. If the real pathogen is encountered later, the immune system can respond quickly and effectively, preventing severe illness, hospitalization or death.

We now have vaccines to prevent more than 30 life-threatening diseases and infections, helping people of all ages live longer, healthier lives

Vaccines cannot always prevent infection, but they can substantially reduce the risk of serious disease.

2. Evidence of effectiveness - lives saved and diseases controlled

Immunization is described by the World Health Organization as a global health success story, saving millions of lives every year.

Effectiveness varies from vaccine to vaccine and from condition to condition, but many routine vaccines are highly effective:

3. Historical successes: Eradication and near-eradication

Because vaccines have been so successful, many people have never seen the devastating effects of diseases like polio, measles, diphtheria or meningitis. When vaccination rates decline, these diseases can—and do—return.

4. Community protection - herd immunity

Vaccines protect the individual and the community:

> “Herd immunity,” also known as “community immunity,” happens when enough of the community is immune to a particular disease, either because of vaccination or natural infection, that it makes it less likely to spread from one person to another.

This concept is called community immunity, or herd immunity. And it’s an important reason for you and your family to get vaccinated — so you can help keep yourselves and your community healthy.

When a significant portion of a population is vaccinated, the spread of the pathogen is significantly reduced, limiting transmission and protecting vulnerable populations such as infants, elderly, and immunocompromised people who cannot be vaccinated.

In summary, extensive research, decades of global use, and continuous safety monitoring show vaccines are safe, highly effective, and essential at every age for preventing disease, reducing severe illness and death, and protecting communities as a whole. If you have questions about specific vaccines, talk to a healthcare provider for evidence-based guidance.