The termsimmunizedandvaccinatedare often used interchangeably, but they have different meanings.
Vaccination describes the act of receiving a vaccine.
Immunization describes the process of becoming immune through vaccination.
Verywell / Mayya Agapova
Those differences may seem minor.
Still, using terms correctly can prevent misunderstandings with your healthcare provider.
Verywell / Mayya Agapova
How Are Vaccination and Immunization Different?
Get our printable guide for your next doctor’s appointment to help you ask the right questions.
The World Health Organization (WHO) says vaccination and immunization are related terms.
But vaccination describes a specific action, while immunization describes a process.
The aim was to induce a mild infection that would afford immune protection to the inoculated person.
Variolation is no longer used today.
It was replaced by the smallpox vaccine, a far safer and effective option.
The smallpox vaccine remains an important tool for emergency response in the event of a smallpox outbreak.
What Vaccines Do
Vaccination and immunization involve the use of vaccines.
They are not the same as your body’s response to anatural infectionlike measles or flu.
Vaccines use substances found on the infectious organism (antigens) that the immune system recognizes as foreign.
The immune system produces antibodies (immune proteins) to flag antigens for destruction.
Some of these antibodies are defensive, coordinating the immune response to neutralize an invader.
Others create memory cells that re-launch an attack if the invader returns.
The response your body has to the vaccine is not you getting sick with the illness or disease.
Rather, your body is effectively mounting an immune response.
Side effects of vaccines can include headache, fever, chills, body aches, and fatigue.
For vaccines that don’t afford lifetime protection, revaccination or booster shots may be needed.
Herd immunity doesn’t work for every disease.
Some viruses change significantly in a short time, such as the virus that causes COVID-19.
Some diseases can be spread by people who don’t have symptoms.
And, for some diseases the immune protection is not long-lasting after vaccination or recovering from the disease.
To date, the only disease that has been eradicated across the world is smallpox.
jot down of Vaccines
There are several categories of vaccines that induce immunity in different ways.
The six main categories of vaccines are:
What Are Immunization Schedules?
The schedule describes which vaccines should be given when and in how many doses.
The immunization schedule starts at birth and continues into adulthood.
ACIP considers:
The final vaccine recommendations include the
The CDC sets immunization schedules based on ACIP’s recommendations.
The CDC director adopts the schedules after ACIP approves them, annually in October.
The number of doses can vary by the vaccine formulation used.
The 2025 schedule adopted in October 2024 includes:
How Are Vaccines Approved?
Vaccines in the United States get approval from the Food and Drug Administration (FDA).
Postmarketing clinical trials are studies that are conducted after a vaccine is approved.
These studies can help identify side effects not seen in earlier trials.
Immunization is the process of developing immunity.
The word usually refers to immunity through vaccination, but it can occur through infection as well.
Vaccines teach your immune system to recognize and fight specific pathogens.
Vaccines are timed to protect you and your children when you’re most vulnerable to certain pathogens.
It’s important to follow the CDC’s vaccine schedules.
Get our printable guide for your next doctor’s appointment to help you ask the right questions.
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Boylston A.The origins of inoculation.J R Soc Med.
Centers for Disease Control and Prevention.Possible side effects from vaccines.
Cedar Sinai.Why some vaccines last a lifetime and others don’t.
Association for Professionals in Infection Control and Epidemiology.Herd immunity.
Centers for Disease Control and Prevention.History and epidemiology of global smallpox eradication.
U.S. Department of Health and Human Service.Vaccine types.
Centers for Disease Control and Prevention.Children and adolescent immunization schedule by age.
Centers for Disease Control and Prevention.Who sets the immunization schedule?
Centers for Disease Control and Prevention.Adult immunication schedule by age.
U.S. Food & Drug Administration.Vaccine Development 101.
Zhang L, Wang W, Wang S.Effect of vaccine administration modality on immunogenicity and efficacy.Expert Rev Vaccines.
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