The most common vaccine for these three diseases is a combination vaccine for diphtheria, tetanus, and acellular pertussis, abbreviated as DTaP. The acellular pertussis is a less reactive version of the pertussis vaccine than the whole-cell pertussis DTP vaccine that was used before the mid-1990s. This decreased reactivity makes the DTaP vaccine safer than the old DTP vaccine. This vaccine is scheduled to be given at two, four, and six months, with another booster at fifteen to eighteen months and a final booster at four to six years.
A new variation of this vaccine is Tdap. This vaccine is recommended for adolescents and adults in order to boost their immunity to pertussis. The tetanus (T) component of the vaccine is the same as DTaP, but the diphtheria (d) and acellular pertussis (ap) have less diphtheria toxoid and less pertussis antigen than in DTaP. The schedule for this vaccine for children is once at age eleven or twelve.
Adults are recommended to substitute Tdap for their next tetanus booster vaccine and then continue with the regular tetanus boosters for the rest of their lives. Healthcare workers and any new parent or infant caretakers, especially of infants less than twelve months old, are recommended to get Tdap as soon as possible, even if they received a tetanus booster recently. This recommendation is aimed at preventing the spread of pertussis to infants who are more likely to have a severe case.
The value of the Tdap recommendation for healthcare workers was driven home to us by a CDC report published in June 2008. It reported on a healthcare worker in Texas who unknowingly spread pertussis to eleven infants on a maternity ward. She had been appropriately vaccinated as a child but had not received the Tdap vaccination because it was not yet available in 2004. During the investigation, she was the only healthcare worker who tested positive for pertussis. Of the eleven infants, four were admitted to the pediatric intensive care unit, and five others were admitted to the general pediatric hospital. Fortunately, none of the affected infants died.
There are two brands of the Tdap vaccine: Adacel and Boostrix. The Adacel vaccine is approved for people ages eleven to sixty-four years. The Boostrix vaccine was originally approved for ages ten to eighteen years but received an expanded approval in December 2008 that extended its use to include ages ten to sixty-four years.
Other variations of this vaccine include the DT and Td vaccines. The DT vaccine is suggested for children younger than seven years of age when the pertussis vaccine is not recommended. It provides the pediatric dose of diphtheria and tetanus without any pertussis. It can be used in place of DTaP at any point in the schedule that the DTaP vaccine is recommended. The Td vaccine is the adolescent and adult booster for tetanus and diphtheria and is recommended for people seven years of age and older. It should be given once every ten years (unless Tdap is preferred).
Finally, there is a tetanus-only version of the vaccine for when both diphtheria and pertussis are not recommended. This is only approved for individuals seven years of age and older.
All of these vaccines are inactivated, or killed, vaccines.