Are vaccines an effective tool to prevent disease?

Yes, vaccines are highly effective, safe, and critical tools for preventing infectious diseases. Major scientific and public health organizations worldwide—including the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC)—recognize vaccination as one of the most successful and cost-effective public health interventions in human history.

Key Evidence of Vaccine Effectiveness

•Millions of Lives Saved Annually: Childhood vaccinations prevent approximately 4 million deaths worldwide every year.

•Long-Term Global Impact: The WHO estimates that immunization programs will prevent more than 50 million deaths globally between 2021 and 2030, including nearly 19 million deaths from measles and 14 million deaths from Hepatitis B.

•Decades of Success in the U.S.: According to the CDC, routine childhood vaccinations for children born in the United States between 1994 and 2023 will prevent an estimated 508 million illnesses, 32 million hospitalizations, and over 1.1 million deaths over their lifetimes.

•Eradication and Control of Deadly Diseases: Vaccines are the reason smallpox—a disease that killed hundreds of millions of people—was officially eradicated in 1980. Diseases like polio, diphtheria, measles, and rubella, which once caused widespread death and lifelong disability, are now extremely rare in countries with high vaccination rates.

How Vaccines Work

Vaccines work by introducing a safe, inactive, or weakened part of a pathogen (or a blueprint to make one, as in mRNA vaccines) into the body. This trains the immune system to recognize and fight the virus or bacteria. If the vaccinated person is later exposed to the actual pathogen, their immune system is already primed to quickly destroy it before it can cause severe disease.

Important Nuances

•No Vaccine is 100% Perfect: "Breakthrough infections" (getting sick despite being fully vaccinated) can happen. This occurs because of individual differences in immune systems and the mutation of certain viruses.

•Prevention of Severe Illness: Even when a vaccine does not completely prevent an infection, it remains highly effective at preventing the most dangerous outcomes. A vaccinated person who gets infected is significantly less likely to experience severe symptoms, require hospitalization, or die compared to someone who is unvaccinated.

•Herd Immunity (Community Protection): When a high percentage of a population is vaccinated, it becomes difficult for a disease to spread. This "herd immunity" is vital for protecting vulnerable individuals who cannot get vaccinated, such as newborns, people undergoing chemotherapy, or individuals with severe allergies.

Ultimately, keeping up-to-date with recommended vaccines is the single most effective way to protect yourself, your family, and your community from preventable, life-threatening diseases.

Citations (5)

1cdc.govGovernment
cdc.gov
Backs: “Yes, vaccines are highly effective, safe, and critical tools for preventing infectious diseases. Major scientific and public health organizations worldwide—including the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC)—recognize vaccination as one of the most successful and…”
2cdc.govGovernment
cdc.gov
Backs: “Yes, vaccines are highly effective, safe, and critical tools for preventing infectious diseases. Major scientific and public health organizations worldwide—including the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC)—recognize vaccination as one of the most successful and…”
3cdc.govGovernment
cdc.gov
Backs: “Decades of Success in the U.S.: According to the CDC, routine childhood vaccinations for children born in the United States between 1994 and 2023 will prevent an estimated 508 million illnesses, 32 million hospitalizations, and over 1.1 million deaths over their lifetimes. Eradication and Control of Deadly Diseases:…”
4cdc.govGovernment
cdc.gov
Backs: “Diseases like polio, diphtheria, measles, and rubella, which once caused widespread death and lifelong disability, are now extremely rare in countries with high vaccination rates. How Vaccines Work”
5who.intGovernment
who.int
Backs: “No Vaccine is 100% Perfect: "Breakthrough infections" (getting sick despite being fully vaccinated) can happen. This occurs because of individual differences in immune systems and the mutation of certain viruses.”