Questions & Answers

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When did diphtheria vaccine become available?
The first inactivated toxin, or toxoid, against diphtheria was developed around 1921, but it was not widely used until the 1930s. In the 1940s, diphtheria toxoid was combined with pertussis vaccine and tetanus toxoid to make the combination DTP vaccine.

In 1991, DTaP vaccine was licensed in the United States. The diphtheria component of this combination vaccine is the same as in the DTP vaccine; however, the pertussis component is a more purified "acellular" version, which produces fewer side effects.

In 2005, two new tetanus toxoid-diphtheria-acellular pertussis (Tdap) vaccines were licensed. These vaccines are the first pertussis-containing vaccines that can be given to persons older than 7 years.

Diphtheria is not available as a single antigen vaccine.

What kind of vaccine is it?
The diphtheria vaccine is an inactivated toxin called a toxoid. It is made by growing the bacteria in a liquid medium and purifying and inactivating the toxin.

DTaP and Tdap vaccines are "inactivated" vaccines. Inactivated vaccines do not contain live bacteria or virus and cannot reproduce, which is why multiple doses are needed to produce immunity.

What's the difference between all the vaccines containing diphtheria toxoid?
Diphtheria and tetanus toxoids can be combined as DT (for children younger than age 7 years) or as Td (for persons age 7 years and older). It can also be combined with tetanus and pertussis as DTaP (for children younger than age 7 years) or as Tdap (for persons ages 10 through 64 years). Lastly, DTaP is also part of four childhood combination vaccines that include other vaccines (e.g., IPV, Hib, HepB).

Children age 7 years and older as well as adults are given a different vaccine -- either Td or Tdap.

How is this vaccine given?
The DTaP, DT, Td, and Tdap preparations are all given as an injection in the anterolateral thigh muscle (for infants and young toddlers) or in the deltoid muscle (for older children and adults).

Who should get this vaccine?
Infants should receive DTaP vaccine as part of their routine immunization. Adults should be given a routine booster dose of Td every 10 years. A single dose of Tdap is recommended for persons age 11 years and older in place of one of the Td doses, preferably the first one.

How many doses of DTaP vaccine are recommended?
The usual schedule for infants is a series of four doses given at two, four, six, and 15-18 months of age. A fifth shot, or booster dose, is recommended at 4-6 years of age, unless the fourth dose was given late (after the fourth birthday).

Because immunity to diphtheria wanes with time, individuals should receive a booster dose of Td (adult tetanus and diphtheria) every ten years. A one-time dose of Tdap vaccine should be substituted for one booster dose of adult Td.

Should adults who weren't vaccinated as children receive this vaccine as adults?
Yes. Adults or children ages seven years and older without documentation of tetanus and diphtheria vaccination should receive a primary series of three doses of tetanus and diphtheria toxoid (Td). The first two doses should be separated by 4-8 weeks, and the third dose given 6-12 months after the second dose. Tdap vaccine should be substituted for one of these three doses, preferably the first dose.

Who recommends this vaccine?
The Centers for Disease Control and Prevention (CDC), the American Academy of Pediatrics (AAP), and the American Academy of Family Physicians (AAFP) all recommend this vaccine.

How safe is this vaccine?
Most people have no serious reactions from DTaP vaccine. The most common reactions are local reactions at the injection site, such as soreness, redness, and swelling. Other possible reactions may include fussiness, mild fever, loss of appetite, tiredness, and vomiting. The use of the more purified DTaP instead of DTP has decreased even these mild reactions. Tdap is a new vaccine but trials have shown it to be safe.

What side effects have been reported with this vaccine?
About 20%-40% of children have some local reaction such as pain, redness, or swelling after the first 3 doses of DTaP. Such local reactions seem to be more frequent after the fourth and/or fifth doses. A temperature of 101° F or higher is reported in 3%-5% of DTaP recipients. Less common reactions (persistent crying, higher fever, febrile seizure) are rare and generally occur in fewer than 1 in 10,000 doses.

If a child has a medical reason not to receive the pertussis component of the DTaP vaccine, they can and should still be vaccinated against just diphtheria and tetanus with DT-pediatric vaccine.

The most frequently reported side effects following vaccination with Tdap were headache, generalized body aches, and tiredness.

For adults receiving Td vaccine, localized non-serious side effects are common (redness, soreness, etc.) but are generally self-limiting and require no treatment. Receiving more doses than recommended of any tetanus toxoid-containing vaccine can lead to increased local reactions, such as painful swelling of the arm, so it important for adults to keep an up-to-date record of all their vaccine doses.

How effective is this vaccine?
Approximately 95% of individuals have a protective level of antitoxin in their blood after a properly spaced primary series of vaccine (four doses of DTaP for young children, three of Td/Tdap for adults).

Who should NOT receive diphtheria vaccine?
People who have had a serious allergic reaction to a vaccine component or a prior dose of DTaP, DT, Td, or Tdap vaccine should not receive another. Persons with a moderate or severe illness should postpone receiving the vaccine until their condition has improved.

Can the vaccine cause diphtheria?
No.

Questions and answers about diphtheria disease

Technically reviewed by the Centers for Disease Control and Prevention, February 2009