How Much Do You Really Know About Vaccines?

Despite saving millions of children's lives, they are still widely misunderstood. Take our quiz to boost your immunization IQ.

A. Tdap (tetanus, diphtheria, and pertussis)B. MMR (measles, mumps, and rubella)C. Varicella (chicken pox)D. All of the aboveE. Pregnant women should not get vaccines.

Antibodies that help fight off tetanus, diphtheria, and pertussis weaken with time, putting both you and your baby at risk. Studies suggest that up to 40 percent of infants catch pertussis, also known as whooping cough, from their mothers. When you get the Tdap vaccine between 27 and 36 weeks of every pregnancy, you lower your chances of getting whooping cough and pass along some of the antibodies that will help protect your unborn child for the first two months, until she gets inoculated. Pregnant women should not get vaccines made with live viruses like measles or chicken pox. "There is concern that the virus could cross the placenta and then affect the baby," explains Neal Halsey, M.D., director of the Institute for Vaccine Safety at Johns Hopkins University, in Baltimore.

Vaccines cause autism.

A slew of studies have proven that there is no link between autism and vaccines, and the researcher who first proposed the idea has been discredited. Still, this fallacy persists. "Parents want a reason for their child's problems," says Susan Hyman, M.D., chief of neurodevelopmental and behavioral pediatrics at the University of Rochester Medical Center, in New York. "Vaccines have become the scapegoat because certain red flags of autism, like lack of eye contact and communication, are more noticeable around the 12- to 18-month mark, after a child receives a series of vaccines." While we still don't know exactly what causes autism, decades of studies show that the disorder is equally prevalent among vaccinated and unvaccinated children.

What percentage of the population needs to be vaccinated for herd immunity to be effective?

A. 30 percent B. 50 percentC. 75 percentD. 90 percent

Surprised? If you're going to postpone or skip certain vaccines for your child, you better hope that almost everyone else around him is immunized. "It's like choosing not to use a car seat in the hope that others will drive safely and keep your kid from harm," says Dean Blumberg, M.D., chief of pediatric infectious diseases at the UC Davis Children's Hospital, in Sacramento.

Most recent outbreaks of measles and whooping cough occurred among those who weren't vaccinated. And some disease-causing bacteria like tetanus are not spread from person-to-person. Instead, they're present everywhere in the environment, including in soil and dust, which means an unvaccinated child is defenseless even when his vaccinated peers are protected. This is where herd immunity becomes important. "Herd immunity cuts down on the risk of infection among those who can't get vaccinated, such as newborns. The elderly, pregnant women, and those with compromised immune systems due to autoimmune diseases, cancer, or other illness also benefit," says Dr. Blumberg.

A. Run a slight feverB. Have trouble breathingC. CryD. Experience swelling or tenderness at the injection site

Mild reactions like low-grade fever or soreness at the injection site go away within a few days, and most kids cry for a few seconds when poked with a needle. Rarely, a child may have an allergic reaction to substances like eggs, gelatin, or yeast found in certain vaccines. The odds of severe allergic reactions like throat swelling and labored breathing are less than one in a million, and tend to happen while still at the doctor's office. Other rare reactions may not appear for an hour or more. You should immediately call your pediatrician if your baby develops severe hives, seems limp or unresponsive, has difficulty breathing, has a seizure, or cries nonstop for three or more hours.

You shouldn't take your baby to a theme park -- or travel overseas with her -- until she's 1 year old and can get the measles vaccine.

There's no reason to miss out on a family trip either here or abroad. "Fetuses get some immunity from their vaccinated moms that provides protection for at least the first six months of life," says Matthew Kronman, M.D., an expert in pediatric infectious diseases at Seattle Children's Hospital. Even though measles sickened more than 125 children and adults who visited Disneyland in Anaheim, California, last winter, those visitors have since dispersed, and, at press time, there isn't an ongoing outbreak there.

If you're planning an overseas trip, your pediatrician can give your baby the measles, mumps, and rubella (MMR) vaccine as early as 6 months. However, she'll still need the other two MMR jabs when she's between 12 and 15 months old, and again between ages 4 and 6 years. In fact, you should consult with your doctor any time you are planning to take an overseas trip, to be sure everyone in the family receives vaccines or medications to prevent other infections that might be common where you are traveling.

A. 3 monthsB. 6 monthsC. 12 monthsD. Babies shouldn't get a flu vaccine.

Each year, about 20,000 children age 5 and younger are hospitalized with serious flu-related complications like pneumonia and dehydration. During the 2013-2014 flu season, nearly half of the children who died from the flu were under age 2. The first time your baby gets a flu vaccine, he needs two separate flu shots about a month apart for optimal effectiveness. The first inoculation primes the immune system, then the second starts providing protection. After that, he'll need only one flu vaccination a year.

Once your child is 2 years old and can master the trick of inhaling medication, you have the option of giving an intranasal vaccine instead of a shot. Expectant moms, though, need to stick with the shot, since a nasal spray contains live, weakened viruses. "Vaccination during pregnancy is important because the flu places moms-to-be at high risk for miscarriage, premature birth, pneumonia, and death," notes Dr. Halsey. Plus, the flu-fighting antibodies you'll pass on to your unborn baby can protect him for up to four months after birth.

Your baby will get her first shot before she leaves the hospital.

The hepatitis B vaccine protects against a highly contagious virus that causes lifelong liver disease or cancer in one out of four infected children. Immediate vaccination at hospitals is necessary because many adults who have hepatitis B are symptom-free and don't know they're infected. As a result, they may inadvertently spread the disease to vulnerable infants. For complete protection, your baby will get a second dose at her 1- or 2-month checkup and a third dose between 6 and 18 months.

A. Take him anyway. He's already cranky.B. Reschedule the appointment. You shouldn't give vaccines to a sick child.

You can always check with your doctor first, of course, but generally, there's no reason to reschedule the vaccine appointment. Even if your infant has a stuffy nose, cough, low fever, ear infection, or diarrhea, he can still receive his immunizations. "And if your baby is feeling that poorly, your doctor will want to examine him first and then decide whether to go ahead with the vaccinations or hold off until he improves," says Dr. Halsey. Vaccines are still effective when a child is sick, but occasionally a pediatrician may suggest they be postponed so that Baby doesn't have to deal with side effects like soreness, on top of other discomfort.

A vaccine can lower your baby's risk of diarrhea.

Two different vaccines, RotaTeq and Rotarix, protect against rotavirus, the leading cause of severe diarrhea and vomiting in children. Infants take these liquid vaccines orally at their 2- and 4-month well-care visits. (RotaTeq requires a third dose at 6 months.) Before the vaccine became available, this gastrointestinal disorder claimed the lives of about 20 to 70 children every year and sent up to 70,000 kids to the hospital. "Infants and toddlers are especially vulnerable to dehydration from severe diarrhea and vomiting," says Dr. Blumberg. Vaccinated kids who do get rotavirus tend to have milder symptoms and recover more quickly.

A. Agree to give her two of them. Too many vaccines may overwhelm her immune system.B. Stick to the schedule that your doctor has recommended.

"The goal is to protect infants as early as possible from diseases known to be the most dangerous or fatal to them," says Dr. Blumberg. Because it takes time for a baby's immune system to produce the necessary antibodies to fend off ailments, vaccinations start early and are given in multiple doses over several months. For instance, your baby will receive the pneumococcal vaccine, which protects against pneumonia, ear infections, and meningitis, at ages 2, 4, 6, and 12 months. "The child's immunity gets stronger with each dose," notes Dr. Blumberg. Deviating from the vaccination schedule recommended by the Centers for Disease Control and Prevention and the American Academy of Pediatrics leaves your baby vulnerable to potentially serious, life-threatening ailments.

It's okay for a child to be infected with the chicken pox virus, like at a chicken pox party, instead of getting the vaccine.

Natural infection with the varicella or chicken pox virus carries a lot of danger. Approximately one out of every 1,000 children who gets the virus will develop severe pneumonia or a brain infection. That's a high risk. (Remember, fewer than one in a million kids suffer labored breathing from a vaccine.) Infected kids also have an increased risk of group A streptococcus, a bacterium capable of causing a range of infections, including strep throat and the sometimes fatal disease more commonly known as flesh-eating bacteria. Before the varicella vaccine became available in 1995, chicken pox claimed the lives of one to two children every week. Even though vaccinated kids can still get chicken pox, their symptoms tend to be less severe and don't last as long, since the vaccine has primed their immune systems to knock out the virus.

A. 13B. 26C. 33

Practically every childhood vaccine requires more than one dose, which is why kids receive as many as 26 inoculations by their second birthday. These vaccinations protect against 14 different diseases. Despite your baby's little body and fragile appearance, you can rest assured that he's well equipped to handle this number of immunizations. In fact, studies show that infants can effectively make antibodies to about 100,000 vaccines at once.?

Originally published in the July 2015 issue of American Baby magazine.

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