Are vaccines an effective tool to prevent disease?

Vaccines are proven to prevent disease — I'll pull the evidence for your answer now.

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

Scientific consensus is overwhelmingly supportive of vaccination as a safe and effective means of preventing serious illness.

1. Vaccination is among the most effective prevention methods

•Vaccination is one of the most effective ways to prevent diseases.

•Vaccines are the most effective tool to prevent illness, hospitalizations, and deaths.

WHO's vaccine safety programme notes that over the past 50 years, essential vaccines against just 14 diseases have saved at least 154 million lives. Other WHO estimates are that vaccines prevent 3.5–5 million deaths every year, and

> Over the past 50 years, vaccines have saved more than 150 million lives, as ordinary people chose to protect themselves, their children and their communities from diseases like measles, diphtheria, pertussis, polio, and rotavirus

2. Historical record of disease control and eradication

•Vaccines helped eradicate smallpox in 1977 and

•Throughout history, humans have successfully developed vaccines for a number of life-threatening diseases, including smallpox, meningitis, tetanus, measles and wild poliovirus, with smallpox eradication certified by WHO in 1980 after global vaccination and surveillance efforts.

•They have led to the eradication of smallpox, one of the deadliest diseases in history, and have significantly reduced the incidence of diseases such as polio, measles, and whooping cough.

•In the early 1900s, polio was a worldwide disease, paralysing hundreds of thousands of people every year. By 1950, two effective vaccines against the disease had been developed, and after decades of routine immunization and mass campaigns, in August 2020, the African continent was certified wild poliovirus free.

•Before the measles vaccine was introduced in 1963, major epidemics occurred every few years, causing an estimated 2.6 million deaths annually. Between 2000 and 2023, measles vaccination prevented an estimated 60 million deaths.

•The CDC reports that routine childhood vaccinations have prevented an estimated 42,000 deaths and 20 million cases of disease in the U.S. alone.

3. How effectiveness is achieved

Vaccines work by training the immune system without causing the disease itself:

> Vaccines train our immune systems to create proteins that fight disease, known as ‘antibodies’, just as would happen when we are exposed to a disease but – crucially – vaccines work without making us sick.

They contain weakened or inactive parts of a particular organism (antigen) that triggers an immune response within the body, and prompt the body to produce memory cells so as to rapidly fight it if and when exposed in the future.

Protection is both individual and community-level. 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.

Herd immunity protects those who cannot be vaccinated, such as newborns or those who have compromised immune systems.

4. Measured effectiveness

Effectiveness varies by vaccine and population but is consistently high:

•According to the Centers for Disease Control and Prevention (CDC), most vaccines are about 80–90% effective in preventing disease.

•mRNA vaccines (like Pfizer/Moderna for COVID-19) have shown over 90% effectiveness in preventing hospitalization from the original strains.

•A study completed in 2022 found that the flu vaccine showed a 75% reduction in risk for life-threatening illness in children admitted in the ICU for flu-related symptoms.

Vaccines cannot always prevent infection, but they can substantially reduce the risk of serious disease.

> Vaccination is shown to be quite effective in limiting the more severe course of the disease in symptomatic patients

and high vaccination coverage has been shown to be a reasonably effective tool and may serve in part as a substitute for more stringent government protective measures.

No single vaccine provides 100% protection, and factors such as vaccine type, number of doses, waning antibody levels, age and immune status affect effectiveness. Some vaccines require multiple doses, given weeks or months apart to allow for the production of long-lived antibodies and development of memory cells, and boosters strengthen long-term protection as antibody levels naturally decline.

Overall, the global review data and 50-year history show vaccines are highly effective at preventing infection, severe disease, hospitalization and death, and at reducing or eliminating circulation of pathogens in populations when coverage is high.

Citations (3)

1who.intGovernment
Vaccines and immunization: Vaccine safety
Backs: “Scientific consensus is overwhelmingly supportive of vaccination as a safe and effective means of preventing serious illness. 1. Vaccination is among the most effective prevention methods”
2who.intGovernment
The power of vaccines
Backs: “Over the past 50 years, vaccines have saved more than 150 million lives, as ordinary people chose to protect themselves, their children and their communities from diseases like measles, diphtheria, pertussis, polio, and rotavirus. 2. Historical record of disease control and eradication”
3who.intGovernment
How do vaccines work?
Backs: “Historical record of disease control and eradication. Vaccines helped eradicate smallpox in 1977 and. Throughout history, humans have successfully developed vaccines for a number of life-threatening diseases, including smallpox, meningitis, tetanus, measles and wild poliovirus, with smallpox eradication certified by…”