Are vaccines an effective tool to prevent disease?

Yes, vaccines are one of the most effective and cost-effective public health tools ever developed.

There is an overwhelming consensus among global scientific and medical organizations—including the World Health Organization (WHO), the U.S. Centers for Disease Control and Prevention (CDC), and medical academies worldwide—that vaccines are highly effective at preventing infectious diseases, reducing severe illness, and saving lives.

1. Lives Saved and Diseases Prevented

According to the WHO, immunization currently prevents 3.5 million to 5 million deaths globally every year from diseases such as diphtheria, tetanus, pertussis (whooping cough), influenza, and measles.

•Eradication of Smallpox: In one of the greatest achievements in human history, global vaccination efforts successfully eradicated smallpox, a devastating disease that had killed hundreds of millions of people.

•Near-Eradication of Polio: Polio, which once paralyzed tens of thousands of children annually, has been reduced by over 99% worldwide and is on the verge of total eradication.

•Massive Reduction in Measles Deaths: Globally, measles deaths decreased by 84% in the early 2000s due to accelerated vaccination programs.

2. Broad Societal and Economic Impact

Vaccine programs prevent millions of hospitalizations and save trillions of dollars in healthcare costs and lost productivity.

•A CDC-supported analysis found that routine childhood vaccinations for children born between 1994 and 2023 in the United States alone will prevent an estimated 508 million illnesses, 32 million hospitalizations, and more than 1.1 million deaths, saving nearly $2.7 trillion in societal costs.

3. How Vaccines Work

Vaccines work by introducing a harmless, weakened, or inactive part of a pathogen (or a blueprint to make one, such as with mRNA vaccines) to the body. This "trains" the immune system to recognize and fight the virus or bacteria in the future without the person having to contract the actual, dangerous disease.

4. Community (Herd) Immunity

When a high percentage of a population is vaccinated against a contagious disease, it limits the pathogen's ability to spread. This creates herd immunity, which provides indirect protection to vulnerable individuals who cannot get vaccinated—such as newborns, pregnant women, or individuals undergoing chemotherapy and those with severely compromised immune systems.

5. "Efficacy" vs. "Real-World Effectiveness"

No vaccine is 100% effective for every single person.

•Vaccine Efficacy refers to how well a vaccine performs in highly controlled clinical trials (often showing 80% to 95%+ protection against specific diseases).

•Vaccine Effectiveness measures how well they work in the diverse "real world". Even when a vaccinated person experiences a "breakthrough infection," the vaccine still provides critical protection by dramatically lowering the risk of severe illness, hospitalization, and death.

Ultimately, alongside clean drinking water and sanitation, vaccines are widely recognized as a primary cornerstone of modern medicine and public health.

Citations (7)

1who.intGovernment
who.int
Backs: “There is an overwhelming consensus among global scientific and medical organizations—including the World Health Organization (WHO), the U.S. Centers for Disease Control and Prevention (CDC), and medical academies worldwide—that vaccines are highly effective at preventing infectious diseases, reducing severe illness,…”
2who.intGovernment
who.int
Backs: “There is an overwhelming consensus among global scientific and medical organizations—including the World Health Organization (WHO), the U.S. Centers for Disease Control and Prevention (CDC), and medical academies worldwide—that vaccines are highly effective at preventing infectious diseases, reducing severe illness,…”
3vaccinateyourfamily.orgNot yet classified
vaccinateyourfamily.org
Backs: “There is an overwhelming consensus among global scientific and medical organizations—including the World Health Organization (WHO), the U.S. Centers for Disease Control and Prevention (CDC), and medical academies worldwide—that vaccines are highly effective at preventing infectious diseases, reducing severe illness,…”
4science.org.auNonprofits and think tanks
science.org.au
Backs: “Community (Herd) Immunity. When a high percentage of a population is vaccinated against a contagious disease, it limits the pathogen's ability to spread. This creates herd immunity, which provides indirect protection to vulnerable individuals who cannot get vaccinated—such as newborns, pregnant women, or individuals…”
5who.intGovernment
who.int
Backs: “"Real-World Effectiveness". No vaccine is 100% effective for every single person. Vaccine Efficacy refers to how well a vaccine performs in highly controlled clinical trials (often showing 80% to 95%+ protection against specific diseases).”
6cdc.govGovernment
cdc.gov
Backs: “Even when a vaccinated person experiences a "breakthrough infection," the vaccine still provides critical protection by dramatically lowering the risk of severe illness, hospitalization, and death. Ultimately, alongside clean drinking water and sanitation, vaccines are widely recognized as a primary cornerstone of…”
7nih.govGovernment
nih.gov
Backs: “Ultimately, alongside clean drinking water and sanitation, vaccines are widely recognized as a primary cornerstone of modern medicine and public health. 1.”