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The terms immunization, vaccination, and inoculation are often used interchangeably, but are they really the same thing?
According to the World Health Organization (WHO), “immunization is the process whereby a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine. Vaccines stimulate the body’s own immune system to protect the person against subsequent infection or disease.”
A person becomes immune to a disease when the body has been exposed to it either through illness or vaccination. The immune system develops antibodies to the disease so that it cannot make you sick again.
Immunization describes the actual changes your body goes through after receiving a vaccine.
The US Centers for Disease Control and Prevention (CDC) defines a vaccine as “a product that stimulates a person’s immune system to produce immunity to a specific disease, protecting the person from that disease. Vaccines are usually administered through needle injections, but can also be administered by mouth or sprayed into the nose.”
Vaccination is the process of getting a vaccine into the body or “the act of introducing a vaccine into the body to produce immunity to a specific disease.” A vaccine is what initiates the immunization process.
The definition of inoculation is “to give a person or animal a vaccine—a substance to prevent a disease.” Inoculation is simply the process of giving a person a vaccine.
Vaccination or immunization is a process we use to protect people from potentially deadly diseases. Diseases that used to kill millions of people each year can now be prevented through vaccination.
When you get a vaccine or immunization, the body “sees” the germs that cause the disease and develops protective antibodies. Once your body contains these antibodies, it will be able to fight off the germs if you are ever exposed to them and help prevent you from getting sick. Sometimes this immunity wears off over time, which means additional vaccines may be needed later in life.
Vaccine or Vaccination?
The Quick And Dirty
A vaccine is the liquid or preparation itself, and a vaccination is what you get when someone administers the vaccine to you.
A vaccine is the fluid they inject into you or the aerosol you inhale; it's the preparation of an inactivated microbe or virus that stimulates an immune response that helps protect you from disease. For example, a nurse could say, “The vaccine arrived yesterday.” Picture a tube of liquid.
A vaccination is the shot you get. It’s the introduction of the vaccine into your body. You get a vaccination when someone administers the vaccine to you.
A nurse could say, “We can start giving vaccinations now,” or “We run a vaccination clinic.”
In rare cases, the word 'vaccine' can refer to something that treats disease
We typically think of a vaccination as something that protects you from getting sick if you encounter a bacteria or virus in the future—that’s how the flu vaccine works: it won’t do any good if you get a vaccination after you already have the flu—but occasionally, scientists also use the words “therapeutic vaccine” to describe a treatment that triggers an immune response after a person has been infected with a virus or developed cancer. For example, researchers have worked on Ebola vaccines that might do both—help people resist infection and respond better after they have been infected. Provenge is a therapeutic vaccine that has been approved for prostate cancer treatment.
Why the word 'vaccination' is related to cows
The word “vaccination” was first used in the 1800s to refer to the injection of the cowpox virus to give people immunity to smallpox, a more severe related disease.
In fact, the word “vaccine” comes from a Latin word meaning “from cows.
” According to the Oxford English Dictionary, it was Louis Pasteur who popularized the use of the term more broadly in the late 1800s to refer to any formulation that prevents disease in this way.
- In summary, the vaccine is the liquid or preparation itself, and a vaccination is the act of administering the vaccine.
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- Image courtesy of Shutterstock
Vaccines play an important role in keeping us healthy. They protect us from serious and sometimes deadly diseases — like haemophilus influenzae type b (Hib) and measles.
It’s normal to have questions about vaccines. Vaccines.gov works with scientists and doctors to answer your questions and provide the information you need to get vaccinated.
In this section of the site, you’ll find the answers to common questions like:
Once you have the information you need, make sure that you and your family are up-to-date on your vaccinations — they’re your best shot against serious, preventable illness. Find more answers to common questions about vaccines.
A few helpful terms
As you learn about vaccines and how they protect you, it may be helpful to understand the difference between vaccines, vaccinations, and immunizations.
A vaccine is made from very small amounts of weak or dead germs that can cause diseases — for example, viruses, bacteria, or toxins. It prepares your body to fight the disease faster and more effectively so you won’t get sick.
Example: Children younger than age 13 need 2 doses of the chickenpox vaccine.
Vaccination is the act of getting a vaccine, usually as a shot.
Example: Schedule your tetanus vaccination today.
- Immunization is the process of becoming immune to (protected against) a disease.
- Example: Because of continued and widespread immunization in the United States, it’s rare for Americans to get polio.
- Immunization can also mean the process of getting vaccinated. For example, your “immunization schedule,” is the timing of your shots
LAST REVIEWED: March 2020
Why vaccination is safe and important
Vaccines are the most effective way to prevent infectious diseases. This page explains how vaccines work, what they contain and the most common side effects.
Watch a video of a GP answering a parents' questions about vaccination
Be aware that anti-vaccine stories are spread online through social media.
They may not be based on scientific evidence and could put your child at risk of a serious illness.
Things you need to know about vaccines
- protect you and your child from many serious and potentially deadly diseases
- protect other people in your community – by helping to stop diseases spreading to people who cannot have vaccines
- get safety tested for years before being introduced – they're also monitored for any side effects
- sometimes cause mild side effects that will not last long – some children may feel a bit unwell and have a sore arm for 2 or 3 days
- reduce or even get rid of some diseases – if enough people are vaccinated
- do not cause autism – studies have found no evidence of a link between the MMR vaccine and autism
- do not overload or weaken the immune system – it's safe to give children several vaccines at a time and this reduces the amount of injections they need
- do not cause allergies or any other conditions – all the current evidence tells us that vaccinating is safer than not vaccinating
- do not contain mercury (thiomersal)
- do not contain any ingredients that cause harm in such small amounts – but speak to your doctor if you have any known allergies such as eggs or gelatine
Why vaccines are important
Vaccination is the most important thing we can do to protect ourselves and our children against ill health. They prevent up to 3 million deaths worldwide every year.
Immunization: The Basics
Let’s start by defining several basic terms:
Immunity: Protection from an infectious disease. If you are immune to a disease, you can be exposed to it without becoming infected.
Vaccine: A product that stimulates a person’s immune system to produce immunity to a specific disease, protecting the person from that disease. Vaccines are usually administered through needle injections, but can also be administered by mouth or sprayed into the nose.
Vaccination: The act of introducing a vaccine into the body to produce immunity to a specific disease.
Immunization: A process by which a person becomes protected against a disease through vaccination. This term is often used interchangeably with vaccination or inoculation.
Links to Basic Immunization Information
- Why immunize?
Learn how getting vaccinated can protect your grandchildren, prevent epidemics, and eliminate diseases and their serious consequences.
- Brief overview of adult and childhood vaccine-preventable diseases and vaccines
Read about the serious diseases that cause long-term illnesses, hospitalization, and even death, and which can be prevented by vaccines.
- 10 things a parent should know about immunizations
Includes how many vaccine doses your child needs, the importance of keeping records, side effects, etc.
- How immunity works: types of immunity
Learn the difference between the two basic types of immunity: active and passive.
- Common questions
Find answers to common questions about immunization.
- What would happen if we stopped vaccinations?
See how diseases that are rare today could once again become common—and deadly—if vaccination coverage does not continue at high levels.
- Life-cycle of an immunization program
See how a successful immunization program can lead to a temporary increase in disease. Follow the evolution of a disease, from a time when there was no vaccine untilit is eradicated.
Related Information and Materials
- The Parents’ Guide to Childhood Immunizations
68-page booklet introducing parents to all childhood diseases and the vaccines that can protect children from them
- The Vaccines for Children Program
The Vaccines for Children (VFC) Program offers vaccines at no cost for eligible children through VFC-enrolled doctors. Find out if your child qualifies. Vaccinating on time means healthier children, families and communities.
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Immunizations and Vaccines
Immunizations, or vaccines as they're also known, safely and effectively use a small amount of a weakened or killed virus or bacteria or bits of lab-made protein that imitate the virus in order to prevent infection by that same virus or bacteria.
When you get an immunization, you're injected with a weakened form of (or a fragment of) a disease. This triggers your body's immune response, causing it to either produce antibodies to that particular ailment or induce other processes that enhance immunity.
Then, if you're ever again exposed to the actual disease-causing organism, your immune system is prepared to fight the infection. A vaccine will usually prevent the onset of a disease or else reduce its severity.
The goal of public health is to prevent disease. It's much easier and more cost-effective to prevent a disease than to treat it. That's exactly what immunizations aim to do.
Immunizations protect us from serious diseases and also prevent the spread of those diseases to others. Over the years immunizations have thwarted epidemics of once common infectious diseases such as measles, mumps, and whooping cough. And because of immunizations we've seen the near eradication of others, such as polio and smallpox.
Some vaccines need to be given only once; others require updates or “boosters” to maintain successful immunization and continued protection against disease.
Because proof of immunization is often a prerequisite for enrollment in school or day care, it's important to keep your children up to date on their vaccines. The benefit of doing so is that your children will be protected from diseases that could cause them serious health problems. The recommended immunizations for children 0-6 years of age include:
At one time or another, each of the diseases addressed by these vaccines posed a serious health threat to children, taking their lives by the thousands; today most of these diseases are at their lowest levels in decades, thanks to immunizations.
It's important to keep your child's immunizations on schedule and up to date, but if your child misses a scheduled dose he or she can “catch up” later.The complete updated schedule of immunizations for children ages 0-18 can be downloaded from the CDC web site.
Today, vaccines are considered safe. As with any medication, they can have side effects. In most cases these are usually mild. Most common minor reactions to an immunization are:
- Soreness or redness around the injection site
- Low-grade fever
For the Public
When you get sick, your body makes antibodies to fight the disease to help you get better. These antibodies stay in your body even after the disease is gone, and protect you from getting the same illness again. This is called immunity. However, you don’t have to get sick to develop immunity. You can gain immunity against disease through immunization.
Immunity through immunization
Immunization (or vaccination) protects people from disease by introducing a vaccine into the body that triggers an immune response, just as though you had been exposed to a disease naturally.
The vaccine contains the same antigens or parts of antigens that cause the disease, but the antigens in vaccines are either killed or greatly weakened.
Vaccines work because they trick your body into thinking it is being attacked by the actual disease.
Immunity through immunization happens without the consequence of being ill and without the risk of potential life-threatening complications from the disease.
Once a person is immunized, specific immune cells called memory cells prevent re-infection when they encounter that disease again in the future. However, not all vaccines provide lifelong immunity.
Vaccines such as the tetanus vaccine require booster doses every ten years for adults to maintain immunity.
Not just for children
At any age, vaccination provides the longest-lasting, most effective protection against disease. Vaccine-preventable diseases can be serious, and in some cases can cause life-threatening complications that can lead to hospitalization.
This is especially a concern for infants and young children, who are particularly more vulnerable.
Having children vaccinated on time is important and helps ensure that they receive the protection they need as early as possible to fight off diseases before they are exposed to them.
Immunization is important not only in childhood, but in adulthood as well, to help promote healthy aging.
This is because childhood immunization does not provide lifelong immunity against some diseases such as tetanus (lockjaw) and diphtheria. Adults require helper, or booster, shots to maintain immunity.
Adult vaccinations may also be recommended to protect against disease common in adulthood such as shingles.
Adults who were not adequately immunized as children may be at risk of infection from other vaccine-preventable diseases. They can also infect others. For example, adults who become ill with measles, mumps or pertussis (whooping cough) can infect infants who may not yet be fully immunized.
Since the introduction of vaccines, many serious illnesses have been brought under control.
Immunization can protect you from:
- blood infection
- ear infection
- Haemophilus influenzae type b
- hepatitis A
- hepatitis B
- Human papillomavirus (HPV)
- measles (red measles)
- pertussis (whooping cough)
- rubella (German measles)
- tetanus (lockjaw)
- varicella (chickenpox)
Different Types of Vaccines
The first human vaccines against viruses were based using weaker or attenuated viruses to generate immunity. The smallpox vaccine used cowpox, a poxvirus that was similar enough to smallpox to protect against it but usually didn’t cause serious illness. Rabies was the first virus attenuated in a lab to create a vaccine for humans.
Vaccines are made using several different processes.
They may contain live viruses that have been attenuated (weakened or altered so as not to cause illness); inactivated or killed organisms or viruses; inactivated toxins (for bacterial diseases where toxins generated by the bacteria, and not the bacteria themselves, cause illness); or merely segments of the pathogen (this includes both subunit and conjugate vaccines).
|Vaccine type||Vaccines of this type on U.S. Recommended Childhood (ages 0-6) Immunization Schedule|
|Live, attenuated||Measles, mumps, rubella (MMR combined vaccine) Varicella (chickenpox) Influenza (nasal spray)Rotavirus|
|Inactivated/Killed||Polio (IPV) Hepatitis A|
|Toxoid (inactivated toxin)||Diphtheria, tetanus (part of DTaP combined immunization)|
|Subunit/conjugate||Hepatitis B Influenza (injection)Haemophilus influenza type b (Hib) Pertussis (part of DTaP combined immunization) PneumococcalMeningococcal|
|Vaccine type||Other available vaccines|
|Subunit/conjugate||Human papillomavirus (HPV)|
Live, attenuated vaccines currently recommended as part of the U.S.
Childhood Immunization Schedule include those against measles, mumps, and rubella (via the combined MMR vaccine), varicella (chickenpox), and influenza (in the nasal spray version of the seasonal flu vaccine).
In addition to live, attenuated vaccines, the immunization schedule includes vaccines of every other major type—see the table above for a breakdown of the vaccine types on the recommended childhood schedule.
The different vaccine types each require different development techniques. Each section below addresses one of the vaccine types.
Live, Attenuated Vaccines
Attenuated vaccines can be made in several different ways. Some of the most common methods involve passing the disease-causing virus through a series of cell cultures or animal embryos (typically chick embryos).
Using chick embryos as an example, the virus is grown in different embryos in a series. With each passage, the virus becomes better at replicating in chick cells, but loses its ability to replicate in human cells.
A virus targeted for use in a vaccine may be grown through—“passaged” through—upwards of 200 different embryos or cell cultures. Eventually, the attenuated virus will be unable to replicate well (or at all) in human cells, and can be used in a vaccine.
All of the methods that involve passing a virus through a non-human host produce a version of the virus that can still be recognized by the human immune system, but cannot replicate well in a human host.
When the resulting vaccine virus is given to a human, it will be unable to replicate enough to cause illness, but will still provoke an immune response that can protect against future infection.