DT-Based Combined Vaccines
A combined vaccine is a vaccine that is designed to protect against two or more diseases or against one disease caused by different strains or serotypes of the same organism. Therefore, combined vaccines contain two or more antigens that are either combined by the manufacturer or mixed immediately before administration. Such vaccines are in common use because they allow simultaneous administration of multiple antigens resulting in fewer injections and visits to the clinic. “DT-based combined vaccines”, which contain diphtheria toxoid (D) and tetanus toxoid (T) in combination with other antigens, have been in use since the middle of the 20th century. Some of the earliest DT-based combined vaccines included an inactivated poliomyelitis vaccine (IPV) and/or a whole-cell pertussis vaccine (wP) component. Depending on the antigens included, these were called DT-IPV, DTwP-IPV, or DTwP. These were followed by combinations with various acellular pertussis antigens (aP) as an alternative to wP and with the addition of one or both of Haemophilus influenzae type b conjugates (Hib) and hepatitis B surface antigen (HepB).
Currently there are many DTwP-based and DTaP-based combined vaccines available worldwide that vary in the number of antigens included in the vaccine as well as the amounts of each antigen. In addition, the vaccines differ in the intended age range for use (i.e. infants, toddlers, older children, adolescents and adults). The most complex vaccines currently approved in some countries include DTaP or DTwP together with IPV, HepB and Hib components but it is quite possible that even more extensive combined vaccines may be developed in future.
Vaccines that provide protection against diphtheria, tetanus and pertussis have been part of the WHO Expanded Programme on Immunization (EPI) since its inception in 1974. Other combined vaccines, that is, vaccines that also include HepB, Hib and/or IPV, are increasingly being used in national immunization programmes.
DT-based combined vaccines standardization
WHO Recommendations to assure the quality, safety and efficacy of DT-based combined vaccines was developed and adopted by the Expert Committee on Biological Standardization in its meeting in 2012. The final document will be published in a WHO Technical Report Series (TRS) to replace WHO’s Requirements for diphtheria, tetanus, pertussis and combined vaccines which was published in WHO TRS 800 in 1990. The revised Recommendations for DT-based combined vaccines refer to the following Recommendations for single vaccines:
- Recommendations to assure the quality, safety and efficacy of diphtheria vaccines;
- Recommendations to assure the quality, safety and efficacy of tetanus vaccines;
- Recommendations for whole-cell pertussis vaccine;
- Recommendations to assure the quality, safety and efficacy of acellular pertussis vaccines;
- Recommendations to assure the quality, safety and efficacy of recombinant hepatitis B vaccines;
- Recommendations for the production and control of poliomyelitis vaccine (inactivated);
- Recommendations for the production and control of Haemophilus influenzae type b conjugate vaccines.
Recommendations to assure the quality, safety and efficacy of DT-based combined vaccines, Technical Report Series 980, 2012
- WHO Manual for Quality Control of Diphtheria, Tetanus and Pertussis Vaccines
WHO reference materials for DT-based combined vaccines are reference materials for individual antigen components. Please visit the website for individual vaccines and the catalogue of International reference Preparations.
Prequalified DT-based combined vaccines
The following DT-based combined vaccines are prequalified for procurement by UN organizations:
- Diphtheria and Tetanus vaccine (adsorbed), Abbreviation: DT;
- Diphtheria and Tetanus vaccine (adsorbed, reduced Diphtheria antigen content, for adult use) , Abbreviation: dT;
- Diphtheria, Tetanus and whole-cell Pertussis vaccine (adsorbed) , Abbreviation: DTwP;
- Diphtheria, Tetanus and acellular Pertussis vaccine (adsorbed) , Abbreviation: DTaP;
- Diphtheria, Tetanus, whole-cell Pertussis and recombinant Hepatitis B vaccine (adsorbed) , Abbreviation: DTwP-HepB;
- Diphtheria, Tetanus, Pertussis and Haemophilus influenzae type b conjugate vaccine (adsorbed), Abbreviation: DTwP-Hib (all-in-one), or DTwP+Hib (with separate freeze-dried Hib);
- Diphtheria, Tetanus, Pertussis, Hepatitis B and Haemophilus influenzae type b conjugate vaccine (adsorbed), Abbreviation: DTwP-HepB-Hib (all-in-one), or DTwP-HepB+Hib (with separate freeze-dried Hib).