Are vaccines an effective tool to prevent disease?

Vaccines prevent disease — I'll gather the evidence on how well they work.

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

Evidence from major health authorities:

•World Health Organization (WHO) states: "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"

•WHO also explains that "Vaccination is a simple, safe, and effective way of protecting you against harmful diseases, before you come into contact with them". It works by training your immune system to create antibodies without causing disease.

> "Our immune systems are designed to remember. Once exposed to one or more doses of a vaccine, we typically remain protected against a disease for years, decades or even a lifetime. This is what makes vaccines so effective. Rather than treating a disease after it occurs, vaccines prevent us in the first instance from getting sick."

•WHO estimates "that childhood vaccines alone save over 4 million lives every year."

•Other estimates note vaccines prevent 4-5 million deaths every year worldwide and according to the CDC, vaccines prevent an estimated 2 to 3 million deaths each year.

•U.S. Centers for Disease Control and Prevention (CDC): "Vaccines are available for these potentially dangerous or deadly diseases. Over the years, these vaccines have prevented countless cases of disease and saved lives. 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."

•UNICEF and others describe "Vaccines are the most effective tool to prevent the outbreak of many dangerous diseases, including polio and measles."

Effectiveness for specific diseases:

•Research has indicated that "the polio vaccine is more than 90% effective at preventing polio, while the measles vaccine is only approximately 97% effective at preventing measles after two doses"

•Pneumococcal vaccines are highly effective: "Clinical studies show up to 80% reduction in invasive pneumococcal disease among vaccinated adults."

•Overall, research shows these vaccines are "highly effective at preventing serious pneumococcal infections."

Herd immunity and eradication:

•"Vaccination is the most effective method of preventing infectious diseases; widespread immunity due to vaccination is largely responsible for the worldwide eradication of smallpox and the restriction of diseases such as polio, measles, and tetanus from much of the world."

•Thanks to worldwide vaccination programs, smallpox was declared eradicated in 1980 and polio has been nearly eliminated.

Important nuance:

Like all medical interventions, vaccines are "neither 100 percent risk-free nor 100 percent effective." Effectiveness varies by vaccine, disease, age, health condition, and over time, and boosters may be needed. However, the "Overwhelming weight of scientific evidence demonstrates that vaccines are safe and effective", and a person is "far more likely to be seriously harmed by a disease than by a vaccine".

In summary, scientific consensus from WHO, CDC and global studies supports vaccines as a highly effective, safe, and cost-effective method to prevent infectious diseases, reduce severe illness, hospitalization and death, and provide community protection through herd immunity.

Citations (2)

1who.intGovernment
Vaccines and immunization: What is vaccination?
Backs: “Over the past 50 years, essential vaccines against just 14 diseases have saved at least 154 million lives". WHO also explains that "Vaccination is a simple, safe, and effective way of protecting you against harmful diseases, before you come into contact with them".”
2cdc.govGovernment
Vaccines and the Diseases they Prevent
Backs: “Over the years, these vaccines have prevented countless cases of disease and saved lives. 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."”