Vacunas combinadas

Combined vaccines contain antigens belonging to two or more microorganisms; these vaccines have existed for the last 60 years, ever since the diphtheria-tetanus-pertussis (DTP) vaccine was authorized in 1948. The availability of combined vaccines helps to increase the number of antigens in immunization schedules, with a lower number of injections and greater acceptance by health workers and the general population. Furthermore, these vaccines improve vaccination coverage. Despite the substantial increase in the number of systematic vaccines administered to children (increasing in the last 100 years from 1 to 14 vaccines), the quantity of antigenic components has not only not increased but has actually decreased (from 200 and 1903 to 130 in 2007) due to the availability of increasingly purified vaccines. The upward trend in the number of vaccine immunization schedules in the last few years has stimulated research and development into combined vaccines. Based on the trivalent DTP vaccine, either whole-cell DTP or DTaP, two groups of combined vaccines have been developed and tetravalent, pentavalent and hexavalent forms are currently available with DTPa. There is a third group of combined vaccines that does not contain the DTP vaccine. Finally, there is a heptavalent vaccine in which the conjugate vaccines for meningococcus A and C are added to one of the pentavalent vaccines (whole cell DTP-HB-Hib); this vaccine was presented in March 2007 to the European Medicines Agency for countries in the meningitis belt.