Are vaccines an effective tool to prevent disease?

I'll gather the latest evidence on how well vaccines prevent disease.

Yes, vaccines are widely regarded as one of the most effective tools to prevent disease.

Scientific and public health consensus is that vaccines are one of the most effective tools for preventing serious diseases and are the safest and most effective way to prevent the spread of infectious diseases, including measles, whooping cough and polio.

How vaccines work

Vaccines protect our bodies against specific diseases by triggering the immune system to produce antibodies to "fight them off". They reduce risks of getting a disease by working with your body's natural defenses to build protection.

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

Vaccinations are one of the most impactful public health interventions, saving millions of lives annually and reducing the spread of infectious diseases. The clinical efficacy and effectiveness of vaccines are beyond question, with a wealth of scientific evidence demonstrating their ability to reduce disease incidence and prevalence, prevent severe health complications, and save lives.

Evidence of effectiveness

Global impact:

United States example:
Researchers from the Centers for Disease Control and Prevention (CDC) found that among 117 million children born from 1994-2023, nine routine childhood vaccines prevented 508 million lifetime illnesses, 32 million hospitalizations and 1.13 million deaths. Vaccines prevented more than 500 million illnesses and 1.13 million deaths among children born over the last three decades.

Vaccines are very effective and work well to prevent illness. Most childhood vaccines are over 90% effective at protecting against disease. They are considered the health intervention with the greatest impact on reducing mortality and controlling population growth, second only to access to safe water.

Historical disease reduction and eradication

Vaccines have led to significant reductions in infections and diseases, wherever they are applied.

Nuances

Vaccines are not guaranteed to prevent illness, but they can provide high levels of protection. Effectiveness is not absolute prevention of infection but measurable reduction in severe outcomes — many studies emphasize strong protection, especially against hospitalization and critical illness. However, the benefits extend beyond preventing acute infection to also protecting against long-term immune-related sequelae.

In addition to individual protection, high vaccination coverage contributes to community immunity (herd immunity), protecting vulnerable individuals who cannot be vaccinated, and reduces healthcare burden and transmission.

Decades of scientific research confirming that vaccines are one of the most effective tools for preventing serious diseases supports their continued use as a fundamental public health priority.