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DTaP vs. Tdap: What's the Difference?

cartoon doctors holding vaccine needles

DTaP and Tdap are combination vaccines that protect against three potentially fatal diseases - diphtheria, tetanus, and pertussis (whooping cough). Before these vaccines became widely available, these diseases were rampant, claiming thousands of lives each year. 

Continue reading to learn more about how these vaccines work and the differences between the DTaP vaccine and the Tdap vaccine.

What are diphtheria, tetanus, and whooping cough?


This is a highly contagious and potentially fatal respiratory disease that spreads through coughing and sneezing. Until the 1920s, it was a major cause of illness and death among children. Over 200,000 kids would fall sick with diphtheria every year, resulting in thousands of deaths. While the disease continues to be prevalent in some parts of the world, in the United States, only 3 cases of diphtheria have been reported to the Centers for Disease Control and Prevention (CDC) since 2010. The reason for this dramatic drop is widespread immunization practices with tetanus, diphtheria, and whooping cough vaccines.


Also known as lockjaw, tetanus is a nervous system disease caused by a bacteria found in soil. The bacteria enters the body through cuts or wounds in the skin and releases a toxin that attacks the nervous system, causing severe muscle spasms. Tetanus can be fatal if left untreated. In the United States, the tetanus vaccine has been included in routine childhood immunization since the 1940s. This has led to a steady decline in tetanus cases from over 500 a year a few decades ago to an average of 30 cases per year now. At present, nearly all cases of tetanus occur in people who never got a tetanus vaccine or are not up-to-date on their Td vaccine booster shots, which are needed every 10 years.


Whooping cough or pertussis is a highly contagious disease that causes severe coughing spasms in infants, making it difficult for the baby to swallow or breathe. It can lead to pneumonia, brain damage, seizures, and death. Before the 1940s, there were around 200,000 cases and 9,000 deaths from pertussis each year. After the acellular pertussis vaccine became widely available, the number of cases fell drastically.

What are DTaP and Tdap vaccines?

DTaP and Tdap are combination vaccines that provide immunity against three diseases - diphtheria, tetanus, and pertussis (whooping cough). 

In the United States, the Food and Drug Administration has licensed 12 different combination vaccines to help protect against these diseases. Some of these vaccines protect against diphtheria and tetanus (DT and Td vaccine), while others protect against all three diseases (DTaP and Tdap). Some vaccines protect against these same diseases plus other diseases like polio, hepatitis B, and Haemophilus influenzae type B. 

The CDC recommends diphtheria, tetanus, and whooping cough (pertussis) vaccination for everyone.

At what age is the DPT vaccine given?

Babies are given 3 shots of the DTaP vaccine to build high immunity against diphtheria, tetanus, and whooping cough. Young children receive 2 additional booster shots of the DTaP vaccine to maintain protection through early childhood. The CDC recommends a total of five doses of DTaP vaccines with one shot each at ages 2 months, 4 months, 6 months, 15-18 months, and 4-6 years.

Then, to boost immunity from the diphtheria, tetanus, and whooping cough vaccination completed during childhood, older children should get a booster shot of Tdap between the ages of 11 and 12. If a child didn’t get a booster shot as a preteen, they could get it whenever they visit a healthcare provider the next time.

Do adults need a tetanus vaccine?

Tdap vaccines are recommended for all adults. Those who have never had a shot before should get Tdap, whether they got tetanus toxoid or Td (tetanus-diphtheria) in the past. This should be followed by a booster shot of Td or Tdap every 10 years.

Pregnant women are advised a Tdap shot in the early part of the 3rd trimester. Tdap vaccines are recommended during every pregnancy to protect the baby from whooping cough immediately after birth.

When should Tdap be given?

Doctors give a single shot of Tdap to preteens or teens and adults who need it. Pregnant women get a Tdap shot during the 3rd trimester of each pregnancy. In people over the age of 7 who have never been vaccinated with diphtheria, tetanus, and whooping cough vaccines, doctors may give Tdap as a 3-shot series. This vaccine can also be used to complete the childhood immunization schedule for tetanus, diphtheria, and whooping cough in people over the age of 7 who have incomplete vaccination status. Doctors may also use this combination vaccine in people over 7 years of age in place of Td vaccines every 10 years as a booster shot.

Which child should not receive DTaP vaccination?

Any child who develops a severe and potentially life-threatening allergic reaction after a dose of DTaP should not get another dose. In children who cannot get a whooping cough vaccine, healthcare providers can give a DT vaccine instead of a dose of DTaP. However, such children will not be protected against whooping cough.

Some children should not get certain vaccines due to health conditions. Tell your child’s healthcare professional if your child has ever had seizures, severe swelling, and pain after diphtheria, tetanus, pertussis vaccines, or a condition called Guillain-Barré syndrome. 

Children over the age of 7 years should not get DTaP vaccines. If your child is behind on their immunization schedule, their doctor can provide medical advice about how to catch up.

If your child is not feeling well with mild problems like a cold, they can get diphtheria, tetanus, and whooping cough vaccine. However, if your child is severely ill, the doctor might advise waiting until they recover. 

What’s the difference between DTaP vaccine and Tdap vaccine?

The key difference in DTaP and Tdap vaccines is the type of immunity they provide. The upper case letters in these vaccine names indicate a full-strength dose of the vaccine against that particular disease. Therefore, in Tdap, the uppercase T and lowercase “dap” means this vaccine has a full dose of tetanus but smaller doses of diphtheria and pertussis. The “a” indicates an acellular vaccine, meaning the whooping cough vaccine only has a few parts of the bacteria and not the whole bacteria.

DTaP vaccines have full doses against all three diseases. They are used in children younger than 7 years of age to help build strong immunity against these diseases. Tdap vaccines have full-dose tetanus and smaller doses of diphtheria and pertussis. They are given as a Tdap booster shot at ages 11-12 to maintain immunity and provide continued protection to adolescents and adults. 

Is DTaP stronger than Tdap?

Both DTaP and Tdap vaccines contain inactivated forms of the toxin produced by the bacteria that cause these diseases. The inactivated toxin does not cause disease symptoms but triggers antibody production in the body. The antibodies provide immunity and protect against future infections. 

As mentioned, DTaP has full doses of all three vaccines and is approved for use in children under age 7. Tdap has reduced doses of diphtheria and pertussis vaccines and is approved for use in preteens, teens, and adults. Tdap is often called a booster dose because it boosts the immunity obtained from DTaP given during childhood.

Immunity wanes over time. The current recommendation is for everyone to get a booster shot of Td (tetanus and diphtheria) every 10 years. Tdap and Td can be substituted for each other between the ages of 11 and 64. 


1. https://www.cdc.gov/vaccines/vpd/dtap-tdap-td/public/index.html