Learn why and when your child needs the DTaP and Tdap vaccines.

What is the DTaP vaccine?

The DTaP vaccine protects your child against three serious bacterial infections: diphtheria, tetanus (lockjaw), and pertussis (whooping cough).

Diphtheria is an infection that causes the throat to swell, which can make it hard for children to breathe and swallow. If left untreated, toxins from the bacteria can also damage other organs, leading to paralysis and heart failure. While diphtheria used to be a common cause of death in children in the 1920s, decades of vaccination has made the disease virtually nonexistent in the U.S., though diphtheria outbreaks do still occur overseas.

Tetanus, also known as lockjaw, causes painful muscle spasms that can affect breathing and even cause heart damage. Unlike many other infectious diseases -- which children catch from other kids or adults -- tetanus bacteria live in the soil and are transmitted when a contaminated object (like a rusty nail) cuts the skin. A tetanus infection leads to death in up to 20 percent of cases.

Pertussis, also known as whooping cough, is a highly contagious infection of the lungs that can cause coughing spells (some so severe that children have trouble eating and breathing), and may lead to pneumonia and seizures. Infants under 6 months of age are most at risk. Before the vaccine, whooping cough caused about 9,000 deaths in the U.S. each year; now only about 10 children die from pertussis annually. Most children who get whooping cough are actually infected by adults, not other kids. Thousands of adolescents and adults still get whooping cough every year (immunity wears off over time if adults don't get the necessary booster shots).

What are the recommend DTaP and Tdap vaccine schedules?

The DTaP vaccine is given in single shots: at 2, 4, and 6 months, between 15-18 months, and between ages 4-6.

An additional variation on this shot, called Tdap, is recommended starting at age 11 and then every 10 years. Although adults don't typically face the same serious risks from these diseases as babies and children, the Tdap booster shot is recommended primarily to cut down the number of serious cases of whooping cough, since most infants who contract whooping cough actually catch it from adults.

The DTaP vaccine is safe to be given along with other vaccines.

Who shouldn't get the DTaP vaccine?

While the DTaP vaccine is one of the Centers for Disease Control and Prevention's recommended childhood vaccinations, children who fall into the following categories should not receive it:

  • Kids who are moderately or severely ill (more than just a cold, for example) should wait to get vaccinated.
  • Kids who've had a serious allergic reaction (like a seizure, rectal temperature over 105 F. or nonstop crying for three or more hours) to a previous DTaP shot.
  • Children older than 7 (this group should get the Tdap vaccine).

Talk to your doctor if you're concerned about whether or not the DTaP vaccine is safe for your child. If your child is allergic to the pertussis part, for example, another vaccine called DT is often used as a substitute.

Are there any side effects from the DTaP vaccine?

Contracting diphtheria, tetanus, or whooping cough is much more dangerous than any side effects from the vaccine.

Mild reactions to the DTaP vaccine are common, especially after the fourth and fifth doses. Most side effects are due to the pertussis portion of the vaccination; children who have moderate or severe reactions may be able to receive a DT vaccine instead.

  • Up to 25 percent of children will experience low fever or redness, swelling or pain near the shot site.
  • Up to one-third of children may cry or be fussier after the shot.
  • Up to 10 percent of children may be more tired or have a decreased appetite.
  • Up to 2 percent of children may experience vomiting.

Moderate -- and less common -- reactions to the DTaP vaccine include seizure, nonstop crying for three or more hours, and very high fever (105 F. or higher taken rectally).

As with any vaccine, severe allergic reactions are very rare (less than one in a million cases), but possible. If you notice your child having difficulty breathing, hoarseness or wheezing, hives, paleness, weakness, dizziness, or a rapid heartbeat shortly after receiving any shot, call your doctor right away.

Is the DTaP vaccine really necessary?

Because diphtheria has pretty much disappeared in the U.S., some people may think that getting vaccinated is no longer necessary. Not so. Unfortunately, just because diphtheria is no longer widespread here doesn't mean we're completely safe. "Someone with the disease just has to walk right into the country to cause an outbreak," says Paul Offit, MD, Chief of Infectious Diseases at the Children's Hospital of Philadelphia in Pennsylvania and American Baby magazine advisory board member. "Back in the '90s there was an outbreak of diphtheria in the Soviet Union that caused 50,000 cases in one year. It was a big reminder that this disease is still definitely around and we have to protect ourselves against it."

Whooping cough is still a potentially serious disease for babies. Unlike the other commonly vaccinated against diseases that have steadily declined over time, instances of whooping cough actually spike every five years or so. The reason: "Immunity to whooping cough wears off over time, so the disease can be very common in teens and adults," says Robert W. Sears, MD, author of The Vaccine Book: Making the Right Decision for Your Child. "These groups can easily pass on the disease to infants, so it's important to continue protecting babies by older kids and adults continuing to get Tdap boosters."

In recent years, nearly all cases of tetanus occurred in teens and adults. But experts believe the vaccine is important for babies and young children, who are still at risk -- especially as they grow older and play outside (tetanus bacteria live in the soil).

Sources: Paul Offit, MD, Chief of Infectious Diseases at the Children's Hospital of Philadelphia in Pennsylvania and a member of the American Baby magazine advisory board member. Robert W. Sears, MD, author of The Vaccine Book: Making the Right Decision for Your Child. Michael T. Brady, MD, the Vice Chair of the AAP's Committee on Infectious Diseases. The Children's Hospital of Philadelphia's Vaccine Education Center section on DTaP Vaccination. CDC sections on DTaP Vaccination.

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