Combination Vaccines for Childhood Immunization

Vaccination is one of the most valuable and cost-effective strategies available to medicine in the battle to prevent and control infectious diseases. It is considered to be one of the ten greatest public health achievements of the 20th century (1). In the Americas, vaccination has brought about the eradication of smallpox in 1970 and of polio in 1991; the interruption of indigenous measles transmission in 2002; and the lowest numbers of reported cases of congenital rubella syndrome (CRS) and neonatal tetanus at the onset of the 21st century (1, 2). Over the last four decades, important new and improved vaccines to prevent childhood diseases have been developed; more are in the pipeline. As the number of vaccine-preventable diseases increases, so does the number of injections a child must receive to be fully protected. In 1999, the Recommended Childhood Immunization Schedule in the United States included 10 different vaccines—hepatitis B (Hep B); diphtheria, pertussis, and tetanus (DPT); Haemophilus influenzae type b (Hib); injectable polio vaccine (IPV) or oral polio vaccine (OPV); measles, mumps, and rubella (MMR); and varicella—which required a minimum of 13 injections to immunize a child from birth to age 6 years (3). By 2005, the United States childhood immunization schedule (4) recommended the inclusion of two additional vaccines: the conjugated pneumococcal vaccine (PCV) and the influenza vaccine. At this juncture, OPV was replaced with IPV, and diph-