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Vaccines for Children - A Guide for Parents and Caregivers

Vaccines have contributed to a significant reduction in many childhood infectious diseases, such as diphtheria, measles, and Haemophilus influenzae type b (Hib). Some infectious diseases, such as polio and smallpox, have been eliminated in the United States due to effective vaccines. It is now rare for children in the United States to experience the devastating and often deadly effects of these diseases that were once common in the United States and other countries with high vaccination coverage.

A group of mothers with their infants and toddlers.

The vast majority of vaccines are given to healthy babies, children and adults; therefore, it is critical that vaccines be demonstrated to be safe and effective. Ensuring the safety and effectiveness of vaccines is one of the Food and Drug Administration's (FDA) top priorities. The Center for Biologics Evaluation and Research (CBER) is the center within FDA that has regulatory oversight of vaccines in the United States assuring the availability of safe and effective vaccines.

Because immunization programs of the 20th century were so successful, many of today’s parents have never seen many vaccine-preventable diseases and do not understand the potential for them to re-emerge. If too many individuals choose not to vaccinate themselves or their children, some diseases that are now rare or non-existent in this country may resurface.

The viruses and bacteria that cause vaccine-preventable diseases and death still exist and can cause disease in people who are not protected by vaccines. For example, although measles has not been constantly present in the United States since 2000, sporadic cases continue to occur, primarily from unvaccinated visitors who are bringing the disease into the United States from other countries or unvaccinated U.S. travelers returning to the U.S. from countries where measles is still common, including countries in Europe, Asia, the Pacific, and Africa. The United States began experiencing a large multi-state measles outbreak in December 2014 that started in California and spread to additional states and Mexico. The majority of people who got measles were unvaccinated. The initial patients who were confirmed with measles reported visiting two Disneyland Resort Theme Parks in Orange County, California, from December 17 through December 20, 2014. The source of the outbreak is unknown, but it is likely that a traveler (or more than one traveler) who became infected with measles overseas visited one or both of the Disney parks in December during the time that they were infectious.

Measles is one of the most contagious diseases and can cause severe complications, including pneumonia, swelling of the brain, and death. Outbreaks of infectious diseases, such as measles, serve as a reminder that they are only a plane-ride away and the best way not to get sick is to get vaccinated.

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Benefits and Risks

A vaccine is a medication. Like any medicine, vaccines have benefits and risks, and although highly effective, no vaccine is 100 percent effective in preventing disease or 100 percent safe in all individuals. Most side effects of vaccines are usually minor and short-lived. For example, a person may feel soreness at the injection site or experience a mild fever. Serious vaccine reactions are extremely rare, but they can happen.

"Parents should know that the risk of being harmed by a vaccine is significantly smaller than the risk of serious illness from infectious diseases," says Marion Gruber, Ph.D., director of the Office of Vaccines Research and Review in CBER. "Vaccination is a very important step to get children off to a healthy start."

For more information on potential adverse events or reactions, talk with your healthcare provider, and many vaccines also have FDA-approved labeling for the patient that can be a resource of information. It is important to discuss with your healthcare provider any prior reactions to vaccines and any adverse reactions following vaccination.

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Types of Routinely Administered Vaccines for Children

How vaccines work

Children standing in front of school bus.

Vaccines work by preparing the body’s immune system for future attacks by a certain disease, caused by either viruses or bacteria. Vaccines contain weakened bacteria or viruses, or parts of bacteria or viruses, and mimic these disease-causing agents (which are called antigens). As a result of vaccination, the body’s immune system thinks the antigens from the vaccine are foreign and shouldn’t be in the body, but the antigens don’t cause disease in the person receiving the vaccine. After receiving the vaccine, if the virus or bacteria that cause the real disease then enters the body in the future, the immune system is prepared and responds quickly and forcefully to attack the disease-causing agent to prevent the person from getting sick. Vaccines are frequently given by injection (a shot), but some are given by mouth and one is sprayed into the nose.

There are various types of vaccines that are routinely given to children

Attenuated (weakened) live viruses- These vaccines contain a live virus that has been weakened during the manufacturing process so that they do not cause the actual disease in the person being vaccinated. However, because they contain a small amount of the weakened live virus, people with weakened immune systems should talk to their healthcare provider before receiving them. Examples include vaccines that prevent chickenpox and rotavirus and measles, mumps and rubella.

Inactivated (killed) viruses- These vaccines contain a virus that has been killed so as not to cause disease, but the body still recognizes it and stimulates production of antibodies against the disease. They can be given to individuals with weakened immune systems. Examples include vaccines to prevent polio and hepatitis A.
Subunits- In some cases, the entire virus or bacteria is not required for an immune response to prevent disease; just the important parts, a portion or a "subunit" of the disease-causing bacteria or virus is needed to provide protection. The vaccine to prevent influenza (the flu) that is given as a shot is an example of a subunit vaccine, because it is made with parts of the influenza virus.
Toxoids- Some bacteria cause illness in people by secreting a poison (a toxin). Scientists discovered that weakening the toxins, so that they are “detoxified” does not cause illness. Examples of vaccines that contain toxoids include those to prevent tetanus and diphtheria disease.
Recombinant- These vaccines are made by genetic engineering, the process and method of manipulating the genetic material of an organism. An example of this type of vaccine is those that prevent certain diseases caused by the human papillomavirus (HPV), such as cervical cancer. In this case, the genes that code for a specific protein from each of the virus types of HPV included in the vaccine are expressed in yeast to create large quantities of the protein. The protein that is produced is purified and then used to make the vaccine. Because the vaccine only contains a protein, and not the entire virus, the vaccine cannot cause the HPV infection. It is the body's immune response to the recombinant protein(s) that then protects against infection by the naturally occurring virus.
Polysaccharides- To protect against certain disease-causing bacteria, the main antigens in vaccine are sugar-like substances called polysaccharides; these are purified from the bacteria to make polysaccharide vaccines. However, vaccines composed solely of purified polysaccharides are only effective in older children and adults. Pneumovax 23, a vaccine for the prevention of pneumococcal disease caused by 23 different strains, is an example of a polysaccharide vaccine.
Conjugates- Vaccines made only with polysaccharides do not work very well in young children because their immune system has not fully developed. To make vaccines that protect young children against diseases caused by certain bacteria, the polysaccharides are connected to a protein so that the immune system can recognize and respond to the polysaccharide. The protein acts as a “carrier” for the part of the vaccine that will make protective antibodies in the body. Examples of conjugate vaccines include those to prevent invasive disease caused by Haemophilus influenzae type b (Hib).

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Steps to Take When Your Child is Vaccinated

Review the vaccine information sheets

These sheets explain both the benefits and risks of a vaccine. Healthcare providers are required by law to provide them.

Talk to your healthcare provider about the benefits and risks of vaccinesLearn the facts about the benefits and risks of vaccines, along with the potential consequences of not vaccinating against diseases. Some parents and caregivers are surprised to learn that children can be harmed or die of measles, diphtheria, pertussis, and other vaccine-preventable diseases.

Conditions to make your healthcare provider aware of before vaccinationThis might include being sick or having a history of certain allergic or other adverse reactions to previous vaccinations or their components. For example, eggs are used to grow many influenza (flu) vaccines; therefore, it is important to inform the healthcare provider if a child is severely allergic to eggs.

The packaging of some vaccines that are supplied in vials or prefilled syringes may contain natural rubber latex, which may cause allergic reactions in latex-sensitive individuals; therefore, an allergy to latex is helpful to inform healthcare providers of beforehand.

It is also particularly important to discuss with your healthcare provider which vaccines should or should not be given to children who have weakened immune systems.

Report adverse reactionsAdverse reactions and other problems related to vaccines should be reported to the Vaccine Adverse Event Reporting System, which is maintained by FDA and the Centers for Disease Control and Prevention (CDC). For a copy of the vaccine reporting form, call 1-800-822-7967, or report online towww.vaers.hhs.gov

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Routinely Administered Vaccines for Children

Some of the most commonly administered vaccines are briefly discussed below. A complete list of licensed vaccines in the United States and additional information, such as prescribing information and patient labeling are available at: http://www.fda.gov/BiologicsBloodVaccines/Vaccines/ApprovedProducts/ucm093833.htm.

Diphtheria and Tetanus Toxoids and Acellular Pertussis Adsorbed (DTaP)

Brand Names: Daptacel and Infanrix
What it's for: Prevents the bacterial infections diphtheria, tetanus (lockjaw), and pertussis (whooping cough). This combination vaccine is given as a series in infants and children 6 weeks through 6 years of age, prior to their 7th birthday. Diphtheria can infect the throat, causing a thick covering that can lead to problems with breathing, paralysis, or heart failure. Tetanus can cause painful tightening (spasms) of the muscles, seizures, paralysis, and death. Pertussis, also known as whooping cough, has the initial symptoms of runny nose, sneezing, and a mild cough, which may seem like a typical cold. Usually, the cough slowly becomes more severe. Eventually the patient may experience bouts of rapid coughing followed by the “whooping” sound that gives the disease its common name as they try to inhale. While the coughing fit is occurring, the patient may vomit or turn blue from lack of air. Patients gradually recover over weeks to months.
Common side effects may include: Fever, drowsiness, fussiness/irritability, and redness, soreness, or swelling at the injection site.
Tell your health care provider beforehand if: The child is moderately or severely ill, has had swelling of the brain within 7 days after a previous dose of vaccine, has a neurologic disorder such as epilepsy, or has had a severe allergic reaction to a previous shot.

Tetanus Toxoid, Reduced Diphtheria Toxoid and Acellular Pertussis Vaccine Adsorbed (Tdap)

Brand Names: Adacel and Boostrix
What it's for: Booster shot for kids at 10 or 11 years of age to prevent the bacterial infections diphtheria, tetanus (lockjaw), and pertussis (whooping cough). In addition, Boostrix is approved for all individuals 10 years of age and older, (including the elderly). Adacel is approved for use in people ages 10 through 64 years.
Common side effects may include: Pain, redness and swelling at the injection site, headache, and tiredness.
Tell your health care provider beforehand if: The child is moderately or severely ill, has had swelling of the brain within 7 days after a previous dose of pertussis vaccine, or any allergic reaction to any vaccine that protects against diphtheria, tetanus or pertussis diseases.

Haemophilus b Conjugate Vaccine (Hib)

Brand Names: ActHIB, Hiberix, PedvaxHIB
What it's for: Prevents Haemophilus influenzae type b (Hib) invasive disease. Before the availability of Hib vaccines, Hib disease was the leading cause of bacterial meningitis among children under 5 years of age in the United States. Meningitis is an infection of the tissue covering the brain and spinal cord, which can lead to lasting brain damage and deafness. Hib disease can also cause pneumonia, severe swelling in the throat, infections of the blood, joints, bones, and tissue covering of the heart, as well as death. Both ActHIB and PedvaxHIB are approved for routine administration for infants and children beginning at 2 months and through 18 months and 71 months of age respectively; Hiberix is approved as a booster shot in children 15 months through the age of before their 5th birthday.
Common side effects may include: Fussiness, sleepiness, and soreness, swelling and redness at the injection site.
Tell your health care provider beforehand if: The child is moderately or severely ill, or has ever had an allergic reaction to a previous dose of Hib vaccine.

Hepatitis A Vaccine

Brand Names: Havrix and Vaqta
What it's for: Prevents disease caused by hepatitis A virus. People infected with hepatitis A may not have any symptoms; and if they do have symptoms, they may feel like that they have a mild "flu-like" illness; or they may have jaundice (yellow skin or eyes), tiredness, stomachache, nausea and diarrhea. Young children may not have any symptoms, so when a child’s caregiver becomes sick, that is when it is recognized that the child is infected. Hepatitis A is most often spread by an object contaminated with the feces of a person with hepatitis A, such as when a parent or caregiver does not properly wash his or her hands after changing diapers or cleaning up the stool of an infected person. Both vaccines are approved for use in people 12 months of age and older.
Common side effects may include: Soreness and redness at the injection site, and loss of appetite.
Tell your health care provider beforehand if: The child is moderately to severely ill, or has ever had an allergic reaction to a previous dose of the vaccine.

Hepatitis B Vaccine

Brand Names: Engerix-B and Recombivax HB
What it's for: Prevents infection caused by hepatitis B virus. Hepatitis B is spread when body fluid infected with hepatitis B enters the body of a person who is not infected. Hepatitis B can lead to chronic hepatitis (liver inflammation), liver cancer, and death. The vaccines are approved for individuals of all ages, including newborns. It is particularly important for those at increased risk of exposure to hepatitis B virus such as a baby born to mom who is infected with the virus.
Common side effects may include: Soreness, redness, swelling at injection site, irritability, fever, diarrhea, fatigue/weakness, loss of appetite and headache.
Tell your health care provider beforehand if: The child is moderately or severely ill, or has ever had a life-threatening allergic reaction to yeast or to a previous dose of the vaccine.

Human Papillomavirus Vaccine

Brand Names: Cervarix, Gardasil and Gardasil 9
What it's for: Gardasil prevents anal cancer and associated precancerous lesions caused by human papillomavirus (HPV) types 6, 11, 16, and 18 in people ages 9 through 26 years. In this same age group for females, it is also approved for prevention of cervical, vulvar, and vaginal cancer and the associated precancerous lesions caused by HPV types 6, 11, 16, and 18. Gardasil 9 is for use in females ages 9 through 26 and males ages 9 through 15. Gardasil 9 covers five more HPV types than Gardasil, preventing cervical, vulvar, vaginal and anal cancers caused by any of the following HPV Types 16, 18, 31, 33, 45, 52 and 58. Overall, Gardasil 9 has the potential to prevent approximately 90% of cervical, vulvar, vaginal and anal cancers. Gardasil and Gardasil 9 are also approved for the prevention of genital warts caused by types 6 and 11 in both males and females. Cervarix prevents cervical and associated precancerous lesions caused by HPV types 16 and 18 in females ages 9 through 25 years of age.
Common side effects may include: Headache, fever, nausea, dizziness, fainting, and pain, swelling, redness, itchiness or bruising at the injection site.
Tell your health care provider beforehand if: For Gardasil and Gardasil 9 - the child has had an allergic reaction to yeast or to a previous dose of the vaccine. For Cervarix- the child has had an allergic reaction to a component of the vaccine, or to a previous dose of the vaccine.

Influenza Vaccine (administered with a needle)

Brand Names (for children): Afluria, Fluarix, FluLaval, Fluvirin, Fluzone, Fluarix Quadrivalent, FluLaval Quadrivalent, and Fluzone Quadrivalent
What it's for: Different vaccines are approved for different age groups to prevent influenza disease, caused by the strains of influenza virus that are included in the vaccine.
Influenza, commonly called “flu,” is a contagious respiratory virus that can cause mild to severe illness. The elderly, young children and people with certain health conditions (such as asthma, diabetes, or heart disease) are at high risk for serious influenza-related complications. Complications may include pneumonia, ear infections, sinus infections, dehydration, and worsening of certain medical conditions such as congestive heart failure, asthma or diabetes.
The strains of influenza virus that cause disease in people frequently change, so yearly vaccination is needed to provide protection against the influenza viruses likely to cause illness each winter.
Common side effects may include: Pain, redness and swelling at the injection site, low grade fever, and muscle aches, headache, fatigue and general feeling of being unwell.
Tell your health care provider beforehand if: The child is moderately or severely ill, has immune system problems, or has had Guillain-Barre Syndrome (GBS), a neurological disorder that causes severe muscle weakness. Also, tell your healthcare provider about any allergies, including severe allergies to eggs and any allergic reaction to a previous dose of any influenza vaccine.

Influenza Vaccine, Intranasal (nasal spray)

Brand Names (for children): FluMist Quadrivalent
What it's for: Protects against four different strains of influenza virus included in the vaccine; for children and adults ages 2 through 49 years of age.
Common side effects may include: Runny or stuffy nose and cough.
Tell your health care provider beforehand if: The child is moderately or severely ill, has a weakened immune system, has asthma or recurrent wheezing, or has a history of Guillain-Barre Syndrome (GBS), a neurological disorder that causes severe muscle weakness. Also, tell your healthcare provider about any allergies, including severe allergies to eggs and any allergic reaction to a previous dose of any influenza vaccine. In addition, because of the association of Reye's syndrome with aspirin and wild-type influenza infection, the healthcare provider should be made aware if the child is currently receiving aspirin or aspirin-containing therapy.

Measles, Mumps and Rubella Vaccine

Brand Name: M-M-R II
What it's for: Prevents measles, mumps, and rubella in those 12 months of age and older. Measles is a respiratory disease that causes a skin rash all over the body, and fever, cough and runny nose. Measles can be severe, causing ear infections, pneumonia, seizures, and swelling of the brain. Mumps causes fever, headache, loss of appetite and the well-known sign of swollen cheeks and jaw which is from the swelling of the salivary glands. Rare complications include deafness, meningitis (infection of the lining that surrounds the brain and spinal cord), and painful swelling of the testicles or ovaries. Rubella, also called German Measles, causes fever, a rash, and--mainly in women--can also cause arthritis. Rubella infection during pregnancy can lead to birth defects.
Common side effects may include: Fever, mild rash, fainting, headache, dizziness, irritability and burning/stinging, redness, swelling, and tenderness at the injection site.
Tell your health care provider beforehand if: The child is ill and has a fever or has ever had an allergic reaction to gelatin, the antibiotic neomycin, or a previous dose of the vaccine, has immune system problems, or cancer, or problems with the blood or lymph system.

Meningococcal Vaccine

Brand Names: Bexsero, Menactra, Menveo and Trumenba
What it's for: Prevents certain types of meningococcal disease, a life-threatening illness caused by the bacteria Neisseria meningitidis that infects the bloodstream and the lining that surrounds the brain and spinal cord (meningitis). Neisseria meningitidis is a leading cause of meningitis in young children. Even with appropriate antibiotics and intensive care, between 10 and 15 percent of people who develop meningococcal disease die from the infection. Another 10 to 20 percent suffer complications such as brain damage or loss of limb or hearing. Bexsero is approved for use in those 10 through 25 years of age to prevent invasive meningococcal disease caused by N. meningitidis serogroup B. Menactra is approved for use in infants and children beginning at 9 months of age, as well as for adults through 55 years of age. Menveo is approved for use in those 2 months through 55 years of age. Both Menactra and Menveo prevent meningococcal disease caused by N. meningitidis serogroups A, C, Y and W. Trumenba is approved for use in those 10 through 25 years of age to prevent invasive meningococcal disease caused by N. meningitidis serogroup B.
Common side effects may include: Tenderness, pain, redness and swelling at the injection site, irritability, headache, fever, tiredness, chills, diarrhea and loss of appetite for a short while.
Tell your health care provider beforehand if: The child is moderately or severely ill, has had a severe allergic reaction to a previous dose of meningococcal vaccine or diphtheria toxoid, has a known sensitivity to vaccine components, or a history of Guillain-Barre Syndrome (GBS).

Pneumococcal 13-valent Conjugate Vaccine

Brand Name: Prevnar 13
What it's for: Prevents invasive disease caused by 13 different types of the bacterium Streptococcus pneumoniae in infants, children and adolescents ages 6 weeks through 17 years. In infants and children 6 weeks through 5 years of age, it is also approved for the prevention of otitis media (ear infection) caused by 7 different types of the bacterium. Streptococcus pneumonie can cause infections of the blood, middle ear, and the covering of the brain and spinal cord, as well as pneumonia. Prevnar 13 is also approved for adults 50 years of age and older.
Common side effects may include: Pain, redness and swelling at the injection site, irritability, decreased appetite and fever.
Tell your health care provider beforehand if: The child is moderately or severely ill, has ever had an allergic reaction to a previous dose or component of the vaccine, including diphtheria toxoid (for example, DTaP vaccine).

Poliovirus Vaccine

Brand Name: Ipol
What it's for: Prevents polio in infants as young as 6 weeks of age. Polio is a disease that can cause paralysis or death.
Common side effects may include: Redness, hardening and pain at the injection site, fever, irritability, sleepiness, fussiness, and crying.
Tell your health care provider beforehand if: The child is moderately or severely ill, including illness with a fever, has ever had a severe allergic reaction to a previous dose of polio vaccine, any component of the vaccine, or an allergic reaction to the antibiotics neomycin, streptomycin, or polymyxin B.

Rotavirus Vaccine

Brand Names: Rotarix and RotaTeq
What it's for: Prevents gastroenteritis caused by rotavirus infection in infants as young as 6 weeks of age. Rotavirus disease is the leading cause of severe diarrhea and dehydration in infants worldwide. In the United States, the disease occurs more often during the winter. Before rotavirus vaccines were available, most children in the United States were infected with rotavirus before the age of two. In addition, rotavirus resulted in about 55,000-70,000 hospitalizations and 20-60 infant deaths in the United States each year.
Common side effects may include: Fussiness/irritability, cough/runny nose, fever, and loss of appetite.
Tell your health care provider beforehand if: The child has illness with a fever, a weakened immune system because of a disease, has a blood disorder, any type of cancer, has gastrointestinal problems, has had stomach surgery or ever had intussusception, which is a form of blockage of the intestines, is allergic to any of the ingredients of the vaccine, or has ever had an allergic reaction to a previous dose of the vaccine, or has regular close contact with a member of a family or household who has a weak immune system.

Varicella Virus Vaccine

Brand Name: Varivax
What it's for: Prevents varicella (chickenpox) in children 12 months of age and older. Chickenpox usually causes a blister-like itchy rash, tiredness, headache and fever. It can be serious, particularly in babies, adolescents, adults and people with weak immune systems, causing less common, but more serious complications such as skin infection, scarring, pneumonia, brain swelling, Reye's syndrome, (which affects the liver and brain), and death.
Common side effects may include: Soreness, pain, redness or swelling at the injection site, fever, irritability, and chicken-pox like rash on the body or at the site of the shot.
Tell your health care provider beforehand if: The child is moderately or severely ill, including a fever, has a weak immune system, has received a blood or plasma transfusion or immune globulin within the last 5 months, takes any medicines, has allergies including any life-threatening allergic reaction to gelatin, the antibiotic neomycin, or a previous dose of chickenpox or any other vaccine.

Your healthcare provider may decide to use the following vaccines to prevent the diseases described previously. These are also approved by FDA and could reduce the total number of shots a child receives.

Brand Name: Kinrix
What it’s for: Prevents diphtheria, tetanus, pertussis, and polio in children 4 through 6 years of age (prior to 7th birthday).
Common side effects: Similar to those vaccines described previously for the prevention of diphtheria, tetanus, pertussis, and polio.
Tell your healthcare provider beforehand: See information included in the sections for those vaccines that prevent diphtheria, tetanus, pertussis, and polio.
Brand Name: Menhibrix
What it’s for: Prevents certain types of meningococcal disease, caused by the bacteria Neisseria meningitidisand prevents Haemophilus influenzae type b (Hib) invasive disease in infants and children ages 6 weeks through 18 months.
Common side effects: Similar to those vaccines described previously for the prevention of meningococcal and Hib disease.
Tell your healthcare provider beforehand: See information included in the sections for those vaccines that prevent meningococcal disease and Hib disease.
Brand Name: Pediarix
What it’s for: Prevents diphtheria, tetanus, pertussis, hepatitis B and polio in children 6 weeks of age through 6 years of age (prior to the 7th birthday).
Common side effects: Similar to those vaccines described previously for the prevention of diphtheria, tetanus, pertussis, hepatitis B and polio.
Tell your healthcare provider beforehand: See information included in the sections for those vaccines that prevent diphtheria, tetanus, pertussis, hepatitis B and polio.
Brand Name: Pentacel
What it’s for: Prevents diphtheria, tetanus, pertussis, polio and invasive Hib disease in children 6 weeks through 4 years of age (prior to 5th birthday).
Common Side Effects: Similar to those vaccines described previously for the prevention of diphtheria, tetanus, pertussis, polio and Hib.
Tell your healthcare provider beforehand: See information included in the sections for those vaccines that prevent diphtheria, tetanus, pertussis, polio and Hib.
Brand Name: ProQuad
What it’s for: Prevents measles, mumps, rubella (German measles), and varicella (chicken pox) in children 12 months through 12 years of age.
Common side effects: Fever, measles-like rash and injection site reactions such as pain, tenderness, soreness, redness and swelling.
Tell your healthcare provider beforehand: See information included in the sections for those vaccines that prevent measles, mumps, rubella and chicken pox.
Brand Name: Quadracel
What it’s for: Prevents diphtheria, tetanus, pertussis and polio in children 4 through 6 years of age.
Common side effects: muscle aches, fever and injection site reactions such as pain, swelling and redness
Tell your healthcare provider beforehand: See information included in the sections for those vaccines that prevent diphtheria, tetanus, pertussis and polio.

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Parents and Caregivers are Asking

Should I be worried about the increasing number of vaccines recommended for children?

No. Because of advances in science and manufacturing, it is easier than in the past to be sure that vaccines are highly pure. Vaccines represent only a minor stimulation of the infant immune system compared to the large number of potentially dangerous bacteria and viruses babies routinely encounter: starting immediately after a baby is born; thousands of different bacteria begin to live on the skin and the lining of the nose, throat, and intestines. The baby’s immune system rapidly launches immune responses to these bacteria that prevent them from invading the blood stream.

Are the ingredients that are used to make vaccines safe?

Yes. Each ingredient in a vaccine is included for a reason. Before FDA determines that a vaccine is safe and effective and licenses it for use by the public in the United States, the vaccine is carefully evaluated by FDA scientists and doctors, taking into account the ingredients that make up the entire vaccine.