Are vaccines an effective tool to prevent disease?

Vaccines remain one of the best-studied ways to prevent disease — I'll pull the latest evidence on how well they work.

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

Evidence from the World Health Organization (WHO), the U.S. Centers for Disease Control and Prevention (CDC) and other scientific bodies shows they are highly effective at preventing illness, severe disease, disability and death:

1. Vaccines prevent millions of deaths and illnesses every year

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Vaccination is one of the most effective ways to prevent diseases. Over the past 50 years, essential vaccines against just 14 diseases have saved at least 154 million lives

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Immunization currently prevents 3.5 million to 5 million deaths every year from diseases like diphtheria, tetanus, pertussis (whooping cough), influenza and measles.

•Vaccines are described as also critical to the prevention and control of infectious disease outbreaks.

•Vaccines save at least 4 to 5 million lives every year.

In the United States alone:
> Research shows that 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

2. History shows dramatic disease reduction and eradication

> Vaccines are among the most cost-effective ways to protect against infectious diseases. The introduction of a vaccine has, in many cases, led to a very large decrease in the incidence of the targeted disease — such as the 96% decrease in the incidence of polio that occurred within 7 years of the introduction of the Salk and Sabin polio vaccines

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Smallpox, which killed hundreds of millions, was eradicated in 1980, and polio cases have been reduced by more than 99% since 1988.

•Other examples include:

•Before the measles vaccine was introduced in 1963, epidemics caused an estimated 2.6 million deaths annually, and Between 2000 and 2023, measles vaccination prevented an estimated 60 million deaths.

•Smallpox, polio, measles, diphtheria, tetanus and other diseases were reduced by 95-100% after vaccines were introduced for universal use in children in the U.S.

3. How they work to prevent disease

Vaccines work with your body's natural defenses:

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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.

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Vaccines train your immune system to create antibodies, just as it does when it’s exposed to a disease. However, because vaccines contain only killed or weakened forms of germs like viruses or bacteria, they do not cause the disease

•More specifically,

Vaccines contain weakened or inactive parts of a particular organism (antigen) that triggers an immune response within the body.

Newer vaccines contain the blueprint (DNA or RNA) for producing antigens rather than the antigen itself. This creates antibody-producing memory cells so the body can respond rapidly if exposed in the future.

Vaccines often provide long-lasting immunity to serious diseases without the risk of serious illness, and are much safer than natural immunity, because diseases can be serious and even deadly.

Vaccines are also effective against variants, especially at preventing severe disease, hospitalization and death.

4. Community protection - herd immunity

Vaccines protect not only the vaccinated person but also the community:

> When a lot of people in a community are vaccinated, the pathogen has a hard time circulating because most of the people it encounters are immune.

This is called herd immunity, which is especially important for those people who not only can’t be vaccinated but may be more susceptible to the diseases we vaccinate against.

5. No medical intervention is 100% perfect

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No single vaccine provides 100% protection, and herd immunity does not provide full protection to those who cannot safely be vaccinated. But with herd immunity, these people will have substantial protection

•Efficacy varies by vaccine, disease, and over time, and some vaccines require boosters. Some, like influenza and COVID-19 vaccines, need to be updated due to virus changes, but still greatly reduce risk of severe outcomes.

•Like any medicine, vaccines can cause side effects,

usually very minor and of short duration, such as a sore arm or a mild fever. More serious side effects are possible but extremely rare.

•A person is far more likely to be seriously harmed by a disease than by a vaccine. Vaccine-preventable diseases like measles, meningitis, hepatitis B or polio can cause blindness, deafness, paralysis, brain damage, infertility, cancer and death.

Conclusion: The overwhelming scientific consensus is that vaccines are safe, highly effective, and cost-effective tools for preventing infectious diseases, controlling outbreaks, and saving lives. They do not guarantee absolute protection for every person in every case, but at individual and population levels, they dramatically reduce the burden of disease.

This information is for educational purposes and is not medical advice. Talk to your healthcare provider about which vaccines are recommended for you and your family.

Citations (5)

1who.intGovernment
Know the facts
Backs: “Vaccination is one of the most effective ways to prevent diseases. Over the past 50 years, essential vaccines against just 14 diseases have saved at least 154 million lives. Immunization currently prevents 3.5 million to 5 million deaths every year from diseases like diphtheria, tetanus, pertussis (whooping cough),…”
2cdc.govGovernment
Vaccines and the Diseases they Prevent
Backs: “Vaccines are described as also critical to the prevention and control of infectious disease outbreaks. Vaccines save at least 4 to 5 million lives every year. In the United States alone: Research shows that routine vaccinations for children born during 1994–2023 will have prevented about 508 million illnesses and 32…”
3nature.comAcademic
The necessity of vaccines
Backs: “History shows dramatic disease reduction and eradication. Vaccines are among the most cost-effective ways to protect against infectious diseases. The introduction of a vaccine has, in many cases, led to a very large decrease in the incidence of the targeted disease — such as the 96% decrease in the incidence of polio…”
4who.intGovernment
How do vaccines work?
Backs: “Smallpox, which killed hundreds of millions, was eradicated in 1980, and polio cases have been reduced by more than 99% since 1988. Other examples include:”
5hhs.govGovernment
Vaccines Protect You
Backs: “More specifically, Vaccines contain weakened or inactive parts of a particular organism (antigen) that triggers an immune response within the body. Newer vaccines contain the blueprint (DNA or RNA) for producing antigens rather than the antigen itself. This creates antibody-producing memory cells so the body can…”