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Vaccinations protect against many infections! When you skip vaccines, you leave yourself vulnerable to illnesses such as shingles, flu, and HPV and hepatitis B–both leading causes of cancer.

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If you vaccinate against the illness/disease that you're affected by or worried you may contract, it will prevent you from becoming infected once again or it will reduce the severity of your symptoms.

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10 Reasons to Get Vaccinated

Vaccines are safe.The US has a robust approval process in place to ensure that all licensed vaccines are safe. Potential side effects associated with vaccines are uncommon and much less severe than the diseases they prevent.

Talk with a healthcare professional about vaccines recommended for you and your family

Updated July 2023

Source: Centers for Disease Control and Prevention

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10 Reasons to Get Vaccinated Vaccine-preventable diseases have not gone away.The viruses and bacteria that cause illness and death still exist and can be passed on to those who are unvaccinated and not protected. While many diseases are no longer common in the US, global travel makes it easy for...

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Certain vaccines are required for school, work, travel, and more.

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Students, military personnel, and residents of rehabilitation or care centers, health care workers and others whose job puts them at risk of catching and spreading preventable diseases need to be vaccinated against them.

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Do you believe vaccinations should be mandated

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Yes, for the safety of ourselves and others

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Vaccines are able to train your body to prevent sickness before it even manifests.

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Vaccines can train your body to prevent sicknesses before they even start. They do this by introducing something called an antigen into the body, which imitates an infection and primes the immune system to respond. ¹ That way, if you encounter certain disease-carrying organisms, known as pathogens, ² in the future, your body already has a plan of attack.

"After a vaccination-and once the antigen is recognized as foreign by surrounding cells-it sets a cascade of events in motion that may help provide protection against disease," says Bill Gruber, M.D., Senior Vice President of Vaccine Clinical Research and Development at Pfizer. "The body's first line of defense, the innate immune response, is triggered almost immediately."

Modern immunizations have stamped out smallpox. They've nearly ended polio. And they've brought certain diseases such as measles to historic lows. ³ Vaccines also helped change the course of the global COVID-19 pandemic.

How Vaccines Work: A Simple Explanation

To understand how a vaccine immune response works, it helps to learn a little bit about immune-system cells called B-lymphocytes and T-lymphocytes, or B-cells and T-cells. B-cells produce antibodies that fight off infection. ⁵ T-cells recognize and kill cells infected with a virus or other foreign cells, which can stop the infection from spreading. ⁵ When a vaccine introduces an antigen into the body, those B-cells and T-cells get to work.

Because of that immune response, following immunization some people may experience mild symptoms for a day or two, such as a fever, chills, or feeling tired. ⁶ That's because the body is acting as if it's fighting a mild form of the germ-not because it's infected. Fever is one example of the body's protective responses to fight a pathogen.

"Fortunately, these events for vaccines are typically mild or moderate" says Dr. Gruber.

Vaccination, as well as natural infection, also help produce "memory" B- and T-cells. ⁵ That means if you become ill in the future with the pathogen you're vaccinating against, your immune system is trained to protect you and prevent serious illness.

"That's the basis of vaccination," says Gruber. "Before the pathogen can replicate in the body, you've got antibodies generated to prevent that from happening." He adds that some memory cells can protect a person for life, while others are shorter-lived.

Developing this tailored immune response is not immediate, says Gruber, who warns that it can take several weeks to build up enough antibodies to provide protection. Sometimes, he adds, people need to receive one or more additional doses of a vaccine to build a stronger and durable immune response.

Types of Vaccines

All vaccines teach the immune system to create antibodies to help it fight off a particular pathogen. ¹ However, the method they use to accomplish this goal depends on the underlying vaccine technology. It's a particularly exciting time for vaccine technology. We are seeing the opportunities that may come from matching different pathogens to specific vaccine technologies and shifting from traditional vaccines to mRNA vaccines in some cases.

Traditional vaccines contain a version or part of the virus, bacteria, or other pathogen. ¹ It may be live but weakened, such as in the measles or chickenpox vaccines. Or, it might be dead or inert, such as in the pertussis (whooping cough) or tetanus vaccines.

mRNA (messenger ribonucleic acid) vaccines don't contain any part of the pathogen. Instead, mRNA is a molecule that contains instructions that direct cells to make a protein, or a piece of a protein. 7, 8

mRNA vaccines only became available to the public after 2020, but the technology has been in development for decades, as scientists worked to ensure that safe and effective vaccination was possible with this approach. 7 These advances are particularly beneficial from a global health standpoint, as mRNA vaccines can potentially be produced more rapidly than traditional vaccines, in response to a new threat of infectious disease. ⁶

Help Protect Yourself and Your Community

Benjamin Franklin once said, "An ounce of prevention is worth a pound of cure." Which is to say that it is worth the effort to try to help stop something before it happens rather than trying to contain something after it's begun. This premise is the very nature of vaccines.

And when it comes to immunization, it's important to remember that getting vaccinated doesn't just help protect you. In some cases, it can also help keep your family and community safe from the spread of infection, says Gruber.

"The more people who engage responsibly as a community to get vaccinated," Gruber says, "the better the protection can be."

Originally published, Tuesday, May 05, 2020

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How Vaccines Work: Immune Response and the Body's Reaction

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Find out how vaccines work - and why new RNA vaccines are so exciting to healthcare providers and public health officials alike.

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Last updated 22 April 2022

Our most frequently asked questions. Expand for detailed answers from experts.

In some cases, natural immunity is longer-lasting than the immunity gained from vaccination. The risks of natural infection, however, outweigh the risks of immunization for every recommended vaccine. For example, wild measles infection causes encephalitis (inflammation of the brain) for one in 1,000 infected individuals. Overall, measles infection kills two of every 1,000 infected individuals. In contrast, the combination MMR (measles, mumps and rubella) vaccine results in a severe allergic reaction only once in every million vaccinated individuals, while preventing measles infection. The benefits of vaccine-acquired immunity extraordinarily outweigh the serious risks of natural infection. (For more on this topic, see our .)

Additionally, the Hib ( Haemophilus influenzae type b) and tetanus vaccines actually provide more effective immunity than natural infection.

Yes. Studies demonstrate that infants' immune systems can handle receiving many vaccines simultaneously-more than the number currently recommended. The immunization schedule is based on infants' ability to generate immune responses, as well as when they are at risk of certain illnesses. For example, the immunity passed from mother to child at birth is only temporary, and typically does not include immunity against polio, hepatitis B, Haemophilus influenzae type b, and other diseases that can be prevented by vaccination.

No. Vaccines do not cause autism. This possibility was publicized after a 1998 paper by a British physician who claimed to have evidence that the MMR (measles, mumps and rubella) vaccine was linked to autism. The potential link has been thoroughly explored; study after study has found no such link, and , which had originally published it. Studies were also done regarding the possibility of a link between the preservative thimerosal, which is used in some vaccines, and autism; again, no such link was found.

It's likely that this misconception persists because of the coincidence of timing between early childhood vaccinations and the first appearance of symptoms of autism.

Sources

Gever, J. . MedPage Today. (2010) Accessed 01/25/2018.

Carroll-Pankhurst, C., Engels, E.A., Strickler, H.D., Goedert, J.J., Wagner, J., Mortimer Jr, E.A. . British Journal of Cancer. 2001 Nov;85(9):1295. Accessed 01/25/2018.

The Carter Center. . (20 KB PDF) Accessed 01/25/2018.

Centers for Disease Control and Prevention. . Accessed 01/25/2018.

CDC. . Accessed 01/25/2018.

Sharp, P.M., Hahn, B.H. . Philosophical Transactions of the Royal Society of London. Biological Sciences. 2010 Aug 27;365(1552):2487-94. Accessed 01/25/2018.

Worobey, M., Santiago, M.L., Keele, B.F., Ndjango, J.B., Joy, J.B., Labama, B.L., Dhed'a, B.D., Rambaut, A., Sharp, P.M., Shaw, G.M., Hahn, B.H. Origin of AIDS: contaminated polio vaccine theory refuted. Nature. 2004 Apr 22;428(6985):820-.

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Detailed answers to the most frequently asked questions about vaccination.

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Vaccines teach your immune system how to create antibodies that protect you from diseases.

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Will the Immune System Be Weaker By Relying on a Vaccine?

No, the immune system makes antibodies against a germ, like the chickenpox virus, whether it encounters it naturally or through a vaccine. Being vaccinated against one disease does not weaken the immune response to another disease.

Can a Vaccine Give Someone the Disease It's Supposed to Prevent?

It's impossible to get the disease from any vaccine made with dead (killed) bacteria or viruses or just part of the bacteria or virus.

Only those vaccines made from weakened (also called attenuated) live viruses - like the chickenpox (varicella) and measles-mumps-rubella (MMR) vaccines - could possibly make a child develop a mild form of the disease. But it's almost always much less severe than if a child became infected with the disease-causing virus itself. However, for kids with weak immune systems, such as those being treated for cancer, these vaccines may cause problems.

The risk of disease from vaccination is very small. One live virus vaccine that's no longer used in the United States is the oral polio vaccine (OPV). The success of the polio vaccination program made it possible to replace OPV with the inactivated polio vaccine (IPV), which contains a killed virus form. This change means that polio disease cannot be spread by vaccinated U.S. children. OPV is still used in many other countries, though, with great success in reducing the number of cases worldwide.

Does My Child Need Vaccines if All the Other Kids in School Are Immunized?

It is true that a single child's chance of catching a disease is low if everyone else is fully vaccinated (immunized). But your child is also exposed to people other than those at school. And if one person thinks about skipping vaccines, chances are that others are thinking the same thing. Each child who isn't immunized gives highly contagious diseases one more chance to spread.

Although vaccination rates are fairly high in the United States, there's no sure way to know if everyone your child has contact with has been vaccinated. That's especially true now that so many people travel to and from other countries. During travel, someone could be exposed to people who got OPV in other countries, which can be risky for anyone who didn't get all their polio vaccines. So the best way to protect your kids is through vaccination.

Can Getting So Many Vaccines at One Time Harm My Baby?

Babies have stronger immune systems than you might think, and they can handle far more germs than what they receive from vaccines. In fact, the amount of germs in vaccines is just a small percentage of the germs babies' immune systems deal with every day.

Sometimes, kids can have a reaction to a vaccine like a mild fever or rash. But the risk of serious reactions is small compared with the health risks from the often-serious diseases they prevent, and do not happen because the baby got several vaccines at once.

A lot of consideration and research went into creating the immunization schedule most doctors use, and it has been proven safe time and time again. Still, some parents choose to use alternative schedules (spreading or "spacing out" vaccines) because they're concerned about the number of shots their babies get at each checkup. This is actually more likely to make a baby sick. Studies show that many babies on alternative immunization schedules never get all the vaccines they need.

Plus, alternative schedules can be a real hassle. Spacing out vaccines over more doctor visits means that you'll have to take your child to the doctor - and your child will have to get a shot - more often.

Why Should My Child Get a Painful Shot if Vaccines Aren't 100% Effective?

Few things in medicine work 100% of the time. But vaccines are one of the most effective weapons we have against disease - they work in 85% to 99% of cases. They greatly reduce your child's risk of serious illness (particularly when more and more people are vaccinated) and give diseases fewer chances to take hold in a population.

It can be hard to watch kids get a shot, but the short-term pain is nothing compared with suffering through a potentially deadly bout of diphtheria, whooping cough, or measles.

Why Do Healthy Kids Need to Be Immunized?

Vaccinations are intended to help keep healthy kids healthy. Because vaccines work by protecting the body before disease strikes, if you wait until your child gets sick, it will be too late for the vaccine to work. The best time to immunize kids is when they're healthy.

Can Vaccines Cause a Bad Reaction in My Child?

The most common reactions to vaccines are minor and include:

redness and swelling where the shot was given

fever

soreness at the site where the shot was given

In rare cases, vaccines can trigger more serious problems, such as seizures or severe allergic reactions. If your child has a history of allergies to food or medicine, or has had a problem with a vaccine before, let the doctor know before any vaccines are given. Every year, millions of kids are safely vaccinated and very few experience serious side effects.

Research continually improves vaccine safety. The American Academy of Pediatrics (AAP) now advises doctors to use a diphtheria, tetanus, and pertussis vaccine that includes only specific parts of the pertussis cell instead of the entire killed cell. This vaccine, called DTaP, has been associated with even fewer side effects.

Do Vaccines or Thimerosal Cause Autism?

No. Many studies have found no link between vaccines and autism. Likewise, a groundbreaking 2004 report from the Institute of Medicine (IOM) found that thimerosal (an organic mercury compound that's been used as a preservative in vaccines since the 1930s) does not cause autism.

Still, some parents have opted not to have their children immunized, putting them at great risk for deadly diseases.

The MMR vaccine, especially, has come under fire even though many scientific reports have found no evidence linking the vaccine to autism. In fact, the study that suggested a possible link between autism and the MMR vaccine was retracted in 2004 and the doctor who published it lost his medical license. Even before it was discredited and declared fraudulent, the study was rejected by all major health organizations, including the AAP, the National Institutes of Health (NIH), the Centers for Disease Control and Prevention (CDC), and the World Health Organization (WHO).

There's also no reason to believe that thimerosal is linked to autism, according to the 2004 IOM report. Still, in an effort to reduce childhood exposure to mercury and other heavy metals, thimerosal began being removed from kids' vaccines in 1999. Now, vaccines for infants and young children contain no or very little thimerosal. And recent studies have not shown any cognitive and behavioral problems in babies who might have gotten these thimerosal-containing vaccines.

So what could explain the increased rates of autism in recent years? First, a broader definition of autism now can apply to more kids who show varying degrees of symptoms. A greater awareness of the condition among health professionals also has led to more diagnoses.

And while the number of children diagnosed with autism may be increasing, the rates of MMR vaccination are not. In London, diagnoses of autistic disorders have been on the rise since 1979, but rates of MMR vaccination haven't increased since routine MMR vaccination began in 1988.

Also, the average age of diagnosis of autism is the same both in children who have and who have not gotten the MMR vaccine. What many researchers are seeing is that a child might have subtle signs of autism before the first birthday - sometimes even in early infancy - but these aren't noticed by parents until they become more obvious.

Wasn't There a Problem With the Rotavirus Vaccine?

Rotavirus is one of the most common causes of diarrhea in young children. In 1999, a rotavirus vaccine was taken off the market because it was linked to an increased risk for intussusception, a type of bowel problem, in babies.

Now, two different rotavirus vaccines (RotaTeq and Rotarix) are available and are very safe. Some studies suggest that they have a very small increased risk for intussusception, but that problem is rare. These vaccines have been shown to prevent most cases of rotavirus infection and almost all severe cases.

The vaccine is now on the regular immunization schedule to be given orally to infants as a liquid during standard vaccination visits - RotaTeq at ages 2 months, 4 months, and 6 months, or Rotarix at ages 2 months and 4 months. Your doctor will have the most current information.

Do Vaccines Cause SIDS, Multiple Sclerosis, Or Other Problems?

There are concerns, many of which circulate on the Internet, linking some vaccines to multiple sclerosis, sudden infant death syndrome (SIDS), and other problems. To date, studies have not shown any connection between vaccines and these conditions. The number of SIDS cases has actually fallen by more than 50% in recent years, while the number of vaccines given yearly continues to rise.

Why Do Kids Need Vaccines for a Disease That's Been Eliminated?

Diseases that are rare or wiped out in the United States, like measles and polio, still exist in other parts of the world. Doctors continue to vaccinate against them because it's easy to come into contact with illnesses through travel - either when Americans travel abroad or when people who aren't fully immunized come to the United States.

In recent years, there have been measles outbreaks in many different states, even though measles was declared eliminated from the U.S. in 2000. (Elimination means that the disease has not been transmitted continuously for over a year, but it doesn't mean there aren't outbreaks.) These cases were mostly among people who did not get vaccinated. Other preventable diseases that had recent outbreaks include whooping cough (pertussis) and mumps.

It's only safe to stop vaccinations for a particular disease when that disease has been eliminated worldwide, as with smallpox.

How Long Does Immunity Last After Getting a Vaccine?

A few vaccines, like the two for measles or the series for hepatitis B, may make you immune for your entire life. Others, like tetanus, last for many years but require periodic shots (boosters) for continued protection against the disease.

The whooping cough (pertussis) vaccine also does not give lifelong immunity, and that may be one reason why outbreaks still happen. Whooping cough isn't a serious problem for older kids and adults, but it can be for infants and young children. Because of this, teens and adults now get a pertussis booster along with the tetanus and diphtheria booster (Tdap) - an important step in controlling this infection, particularly for pregnant women and other adults who will be around newborn babies.

It's important to keep a record of vaccinations so the doctor knows when your kids are due for a booster. Also make sure your kids get the flu vaccine each year. Last year's flu vaccine won't protect someone from getting the flu this year because flu viruses constantly change. The vaccine is updated each year to include the most current strains of the virus.

The flu vaccine reduces the average person's chances of catching the flu by up to 80%. It can't prevent infection by all viruses that can cause flu-like symptoms, though, so it's not a guarantee that someone won't get sick during flu season. Still, if a person who got the vaccine gets the flu, their symptoms usually will be fewer and milder.

How Are Vaccines Studied and Improved?

The FDA's Center for Biologics Evaluation and Research is the government agency that regulates vaccines in the United States. Working with the CDC and the NIH, they continuously research and monitor vaccine safety and effectiveness.

New vaccines are licensed only after thorough lab studies and clinical trials, and safety monitoring continues even after they're approved. There continue to be improvements (such as those already made to the DTaP and polio vaccines) that ease potential side effects and ensure the best possible safety standards.

Where Can I Get Affordable Vaccines for My Child?

Vaccines are one of the best tools we have to keep kids healthy. But they work best when everyone gets them. Vaccines are now required to be covered by health insurance plans at no cost to the patient. Some plans only cover vaccines when they are given by your doctor or at specific locations. So check with your insurance company to make sure. You can also get inexpensive or free vaccines through many local public health clinics and community health centers, and campaigns to vaccinate kids often hold free vaccination days.

The U.S. government's Vaccines for Children program covers Medicaid-eligible, uninsured Alaskan and Native American populations, and some underinsured kids for routine vaccinations up to 18 years of age. The vaccines are provided by the government and given in a doctor's office. But the doctor's visit itself is not covered (unless the child has insurance, including Medicaid). Some public health clinics may cover both the visit and the vaccinations.

Where Can I Learn More About Vaccines?

Read this article for details about each recommended vaccine. You also can visit the CDC's National Immunization Program website for more information about vaccinations.

And talk with your doctor about which vaccines your kids need. Working together, you can help keep your family healthy.

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Common Questions About Vaccines (for Parents) - Nemours KidsHealth

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Vaccines protect kids from potentially deadly diseases. Learn about what they are, how they work, and what they do.