Vaccines: What Are the Side Effects?

The U.S. Centers for Disease Control and Prevention (CDC) lists 14 diseases against which it recommends that infants and school-age children receive vaccinations. But not all parents are confident in the science or public policy supporting childhood vaccinations.

The CDC publishes a vaccination schedule, developed with other medical organizations, that outlines when doses should be administered. Although each state has different requirements, Pennsylvania, New Jersey and Delaware all require children to receive vaccinations against most of these 14 diseases. Medical and religious exemptions are allowed.

Parents' Concerns

An April 2010 study in the journal Pediatrics reported that almost 12 percent of parents delayed or refused at least one vaccine recommended by their doctor. By far, the most commonly refused vaccine was the one for adolescent girls against human papillomavirus (HPV) to guard against cervical cancer. This vaccine isn’t on the CDC list of top 14 and isn’t required for school-age children.

In the study, parents’ concerns differed according to vaccine. Parents refusing the chickenpox vaccine said they would rather have their child get the disease.

Fear of autism is a major factor. The study’s author, Gary Freed, notes, “Although peer-reviewed original scientific research and multiple expert committees that have reviewed all available data on this issue have failed to show any association between vaccines and autism, anecdotally the concern continues to affect parents.

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“Our study indicates that a disturbingly high proportion of parents, 1 in 5, continue to believe that some vaccines cause autism in otherwise healthy children.” He concludes that “safety information is not reaching parents in an effective or convincing manner.”

Harris Lilienfeld MD, FAAP, Delaware Valley Pediatric Associates, says he spends a lot of time in his Lawrenceville NJ practice listening to parents’ concerns and explaining the current science. He’s flexible to accommodate some of the issues parents raise in order to “make sure the kids have adequate protection.”

For example, the typical schedule calls for particular clusters of vaccines at 2, 4 and 6 months. Dr. Lilienfeld is willing to separate and spread some of these out so that some are also given at 3, 5 and 7 months. He says he respects parents and is not a dictator. But when they ask, “Is it okay not to get the vaccine?” he says, “The answer is no.”

Protecting the Innocent

“Getting the disease is much more dangerous than getting the vaccination,” says Karyl Rattay, MD, director of Delaware Division of Public Health. Serious complications and death can occur in children without immunity.

Dr. Rattay emphasizes a double benefit for vaccination. “First is the protection of the individual from becoming infected, and second is the benefit to the rest of the community. Every person immunized is a person that is likely not to spread the disease to others.”

Diseases don’t wait until a child starts school to be contagious. Consider how many pregnant mothers and young babies you see in your pediatrician’s waiting room. Significant numbers of people depend on a vaccinated public to protect them, including people on chemotherapy or people who have transplants. “It’s not like with a car seat,” explains Paul Offit MD, director of the Vaccine Education Center at Children’s Hospital of Philadelphia. “People who don’t vaccinate are making decisions for the rest of us.”

Vaccines aren’t always 100 percent effective. There have been unusual situations in which vaccinated individuals later contracted the disease. Experts say that in such cases the disease course has been milder than it would have been without the vaccine.

Adverse Effects

No medicines – vaccines included – are absolutely risk free, acknowledge even the most pro-vaccination experts. Tenderness at the site of the shot, fussiness and short fever are fairly common side effects. High fevers in infants have been known to prompt seizures, which are scary but don’t generally have lasting consequences. Other reactions can occur.

More serious are the rare allergic reactions to a vaccine. People with allergies to eggs or gelatin are generally counseled against getting vaccines with components that include egg or gelatin, such as flu vaccines. Talk with your doctor about your child’s known allergies and previous reactions.

Research into the safety of vaccines continues. For instance, the American Sudden Infant Death Institute is currently sponsoring a study of possible associations between SIDS and the DTaP (diphtheria, pertussis and tetanus) vaccine.

For 20 years, the Vaccine Safety Datalink has collected data from 8 health insurance companies across the U.S. to help identify safety issues.

In addition, theVaccine Adverse Event Reporting System (VAERS) provides a database for doctors and patients to report adverse reactions. A reaction listed on VAERS may be coincidental and does not necessarily indicate it was caused by a vaccine.

The National Vaccine Injury Compensation Program exists to help compensate for harm caused by specific vaccines.

The Vaccines, Diseases and Reactions

In addition to the side effects listed with each vaccine that follows, there is a small chance of severe allergic response or other reactions. The reactions were compiled from medical sources, including the U.S. Centers for Disease Control, the Mayo Clinic and the World Health Organization.

DTaP: Diptheria, Tetanus and Pertussis

Note: Although vaccinations for these three diseases are often combined, Pennsylvania does not require students to be vaccinated against pertussis. A combination diptheria-tetanus vaccination is available.

The diseases: Diptheria is an infectious disease caused by a bacteria. Largely eradicated in industrial nations, it kills one in ten people who get it. Prior to the vaccine, 15,000 Americans died from diptheria yearly. Complications include heart failure and paralysis. Diptheria killed 3,000 worldwide in 2000.

Tetanus (lockjaw) is a bacterial infection most often caused by wound contamination. It kills 2 of every 10 people who get it. Globally, it kills 300,000 newborns yearly. The toxin causes severe muscle spasms, strong enough to break bones in children and disrupt breathing. Children with tetanus require hospitalization in intensive care for several weeks.

Pertussis (whooping cough), caused by bacteria, infects millions of people worldwide and kills more than 250,000. It is especially dangerous for infants. Persistent coughing, vomiting, dehydration, pneumonia and brain damage can occur for periods of 8 weeks.

The reaction: The DTaP (diptheria, tetanus and pertussis) vaccine may cause fever and local reaction in up to half the children and fussiness in one third. Up to 1 in 50 vomit. One percent of children cry for more than three hours. Convulsions are reported in 1 in 12,500 cases, and staring/nonresponsiveness in 1 in 1,750. Reports of brain damage and coma have not been clearly linked to the vaccine.

Hepatitis A

The disease: Hepatitis involves inflammation of the liver. Hepatitis A is spread through contaminated food, water and inadequate hand washing. The U.S. still has about 20,000 cases yearly.

The reaction:  Side effects include soreness (1 in 6), loss of appetite (1 in 12), fatigue (1 in 14) and headache (1 in 25).

Hepatitis B

The disease: Hepatitis B is carried by more than 1 million Americans and kills 4,000-5,000 annually. It is transmitted through contact with the blood or other body fluids of an infected person. Hundreds of millions globally are lifelong carriers. It increases risk of liver cancer, liver damage and cirrhosis.

The reaction: Side effects include soreness at the injection site (1 in 4) and possibly severe allergic reaction in fewer than 1 per million.

Hib (haemophilus influenzae type B)

The disease: Before the vaccine, Hib disease was the leading cause of bacterial meningitis among children under 5 years old in the United States, infecting 1 of every 200 American children younger than age 5. Complications include death, meningitis, seizures, deafness and mental retardation. Globally it still kills about 400,000 young children yearly and infects millions.

The reaction:  The vaccine causes fever in about 1 in 20 children.


The disease: Influenza, caused by a family of viruses, hospitalizes 20,000 children under age 5 each year in the U.S. and kills 100. It can be transmitted through the air by coughs or sneezes or by contact with contaminated surfaces. Different strains of the virus are prevalent each year, matched by annual vaccinations that attempt to address them.

The reaction: : The vaccine can cause fever, wheezing, diarrhea/vomiting and nasal congestion in young children. There is a possible but still-unproven link to Guillain-Barre Syndrome in 1 in one million.

MMR: Measles, Mumps, Rubella (German Measles)

The diseases: Measles is caused by a virus that is readily spread through the air or on surfacesby infected people. Prior to vaccinations in the U.S., 3-4 million people got measles yearly, 48,000 were hospitalized and about 500 died each year. It still infects 10-21 million people worldwide, causing 200,000 -345,000 deaths annually, or about 663 deaths daily. 1 in 10 children who contract measles get ear infections; 1 in 20 pneumonia; 1 in 1,000, encephalitis; 1 or 2 in 1,000 die.

Mumps is spread by salivadroplets in the air from infected people and by contact, even on utensils. Prior to the vaccine's introduction,  It infected about half the children in the U.S., or 200,000 people per year. In addition to its typical symptoms, mumps induces meningitis or encephalitis in 10-20 percent of cases, and death in less than 2 percent of cases. Deafness follows mumps in about 1 in 20,000 cases. Complications in post-pubertal adolescents and adults include inflammation of testicles, breasts and ovaries, pancreas and heart muscle. The latter accounts for deaths, most of which occur in people over 19 years old.

Rubella (German measles) is a virus, spread by respiratory droplets. It is milder in children than for the developing fetus in a pregnant mother. Prior to the vaccine, rubella caused mental retardation and birth defects in up to 20,000 newborns in the U.S. annually. Of the babies born to mothers who had rubella in their first trimester, 20-85 percent have birth defects and neurologic abnormalities.

The reaction:  The MMR vaccine can prompt fever (up to 1 in 6); rash (1 in 20); seizure induced by fever (1 in 3,000 doses); low platelet count (1 in 30,000); serious allergic reaction (less than 1 per million doses); and swollen glands in the neck and other temporary side effects. Reports of deafness and long-term brain compromise are so rare that CDC experts are uncertain about any connection with the vaccine. Stronger, more frequent reactions are reported when MMR is combined with the varicella (chickenpox) vaccine.


The disease: The vaccine covers some 23 types of pneumococcus (pneumonia) bacteria, which account for about 1.6 million annual deaths globally, half of them children younger than age 5. It still kills 6,000 Americans annually and hospitalizes almost 200,000. It is responsible for most of this country’s cases of bacterial meningitis and countless ear infections in young children. About 5 percent of children in the U.S. who get pneumococcal meningitis die from it, and up to 35 percent who live have hearing loss, mental retardation and/or paralysis.

The reaction:  The vaccine causes local reaction, drowsiness and mild fever among children in up to half the doses, fussiness in 8 of 10 doses, and fever over 102.2 degrees in about 5 percent of doses.


The disease: Prior to vaccination, polio caused paralysis in up to 20,000 people in the U.S. each year, mostly children. These patients required wheelchairs, braces and/or iron lungs throughout their lives. In 2009, 172 polio cases were reported.

The reaction:  Occasional swelling and redness at the site of injection.

For More Info

American Association of Pediatrics,

Children’s Hospital of Philadelphia, Vaccine Education Center,

State Vaccine Requirements, National Vaccine Information Center,

U.S. Centers for Disease Control,


The disease: This virus is present in stools and is spread hand to mouth, as well as through contaminated water and coughing and sneezing. Rotavirus kills 500,000 children worldwide each year. It causes millions of cases of diarrhea/vomiting in the U.S. annually, 200,000 emergency room visits and up to 70,000 hospitalizations. Most children get at least one case by age 5. Dehydration is one serious complication.

The reaction:  Vaccination may cause irritability. An older vaccine associated with a bowel obstruction called intussusception has been taken off the market. Babies with previous bowel obstruction, however, are at higher risk for this complication than other babies.

Varicella (chickenpox)

The disease: Chickenpox used to infect about 4 million Americans annually, cause 11,000 hospitalizations and more than 100 deaths. Complications include encephalitis (swelling of the brain) and other central nervous system disorders. Serious complications can occur for pregnant women and newborns. The virus remains in the body and can appear as shingles in adults, especially when medically stressed.

The reaction:  The vaccine causes fever in about 1 of 10, a rash in 1 of 25, and rarely, pneumonia and seizures. These side effects are more pronounced and frequent when this vaccine is given with the MMR vaccine. Shingles can result later in life from the varicella vaccination.

Ann L. Rappoport, PhD, is a contributing writer to MetroKids. 

Categories: Health & Nutrition, Medical