Vaccinology is vast and ever changing field. Vaccine research and development and the tools of modern biotechnology have resulted in the licensing and use of vaccines that are safe and effective. Researchers continue to seek new approaches to reducing the number of inoculations given and, in some cases, eliminating the use of needles for administering vaccines. In addition, there is a steady increase in the number of vaccines included in the routine immunisation programme in many low-income countries in Africa. There are moves towards more purified, safer and more effective vaccines as well as increased usage of sophisticated combinations to deliver more vaccines with fewer injections i.e. an increasing role of for combination vaccines.

A combination vaccine is one that combines two or more antigens that prevent different diseases or one that contains multiple strains of infectious agents causing the same disease. The combination vaccines may either be premixed or mixed at time of administration. There are distinct advantages for having combination vaccines.

• For children: There are fewer injections, less trauma in terms of pain and discomfort, and reduced side effects
• For Health Professionals: There is a reduced risk of needle stick injuries
• For parents: There are fewer clinic visits and, thus, a greater likelihood for compliance.

Combination vaccines increase acceptability of multiple vaccines at one visit and vaccinated children get fewer injections and this greatly simplifies vaccination logistics. Combination vaccines may cause some parents to be concerned about antigenic overload, but recent studies show that infants can respond to many antigens at any given time and the immune system can replace two billion CD4+ T cells daily.  (Offit et al. Pediatrics 2002;109:124–9). In fact, “a vaccine is a raindrop in the ocean of what an infant’s immune system successfully encounters every day”

Two examples of combination vaccines are Infanrix hexa (GlaxoSmithKline) and Pentaxim (Sanofi-Pasteur).