Principles of pediatric combination vaccines and practical issues related to use in clinical practice

Background. During the past two decades the number of injections that are required per office visit to fulfill the recommended childhood immunization schedule has increased dramatically. Methods. By reviewing the literature, the principles associated with pediatric combination vaccines are discussed, and practical issues related to their use in clinical practice are evaluated. Results. The ideal combination vaccine is safe, effective and easy to store and use, and its antigenic components fit within the recommended immunization schedule. The ideal combination is associated with fewer adverse reactions than the separately administered antigens, with improved efficacy and higher immune responses compared with its component vaccines. An acceptable combination vaccine must provide comparable efficacy and safety to its component vaccines. Although there are a limited number of combination vaccines already available [diphtheria-tetanus-pertussis, inactivated poliovirus vaccine (IPV) and measles-mumps-rubella], effort is being focused on combining these vaccines with other routine vaccines of infancy including Haemophilus influenzae type b (Hib) and hepatitis B vaccine (HepB). Currently under review by the Food and Drug Administration are diphtheria-tetanus-acellular pertussis (DTPa)-HepB-IPV and DTPa-Hib-IPV combination vaccines, and two DTPa-HepB-IPV-Hib vaccines have been licensed in Europe. As more combination vaccines become available, issues such as interchangeability and administration of extra doses are raised; however, it is important not to miss a vaccination opportunity. Conclusions. The number of injections required to fulfill the recommended childhood immunization schedule at each visit creates problems for patients and practitioner, sometimes risking a missed opportunity for vaccination. The development of combination vaccines will circumvent this problem and increase compliance and vaccination coverage rates.