Challenges in the Development of Combination Vaccines

Abstract

There has been increased interest in the last decade in the development of new vaccines, especially for pediatric use. Newer vaccines that have been licensed and recommended for widespread pediatric immunization include those for Haemophilus influenzae type b (Hib), hepatitis B (HB), and most recently in some countries varicella and Bordetella pertussis (acellular pertussis). Clinical trials are ongoing in infants for vaccines for Streptococcus pneumoniae (pneumococcal), hepatitis A (HA), and Neisseria meningitidis (meningococcal), among others. As a consequence, there is a tremendous opportunity to prevent the morbidity and mortality associated with these infectious diseases and to do so with a significantly favorable cost:benefit. However, each new vaccine would require additional injections which may become so numerous as to discourage widespread immunization. As a consequence, medical practitioners, patients, parents and others are very interested in the development of combination vaccines, whereby individual vaccines are mixed before delivery for administration in a single injection. Such mixing can take place at the point of manufacturing or filling or within a syringe or vial at the time of immunization.