Are vaccines an effective tool to prevent disease?

I'll gather the latest evidence on vaccine effectiveness for disease prevention.

Yes, vaccines are considered one of the most effective tools to prevent disease, according to major public health authorities and scientific evidence.

> Vaccination is one of the most effective ways to prevent diseases

> Vaccination remains one of the most effective tools for preventing infectious disease outbreaks and increasing life expectancy

> The WHO currently ranks vaccination as one of the most effective and cost-effective public health interventions

Key evidence for effectiveness:

More specifically:
> There are now vaccines capable of preventing more than 30 life-threatening diseases, and immunization prevents between 3.5 million and 5 million deaths each year from diseases such as diphtheria, tetanus, pertussis, influenza, and measles

A landmark 2024 WHO study modeled five decades of the Expanded Programme on Immunization and found:
> vaccination against 14 key pathogens has saved an estimated 154 million lives worldwide since 1974

> The measles vaccine accounted for more than 60% of the lives saved

> routine vaccinations for children born during 1994–2023 will have prevented about 508 million illnesses and 32 million hospitalizations and saved over 1.1 million lives

> Two doses of the MMR vaccine are about 97% effective at preventing measles (CDC, 2023)

Beyond individual protection, vaccines generate collective benefits often referred to as herd immunity. This form of immunity protects people who cannot be vaccinated because the virus or bacterium encounters fewer hosts susceptible to infection.

The WHO describes vaccines as "one of the most life-saving public health interventions in history", and the CDC states:
> "Vaccines are among the most successful and cost-effective public health tools available for preventing serious disease and death."

Vaccines are not 100% effective at preventing all infections in all people, and effectiveness can vary by vaccine, disease, age and over time, but they are highly effective at preventing infection, severe disease, hospitalization, death, and transmission for many diseases, and are a central tool for preventing outbreaks.