Alum has been added to protein-based vaccines for more than 60 years and is the most widely used adjuvant, used to increase the immune response to a vaccine. However, adverse events reported following the use of alum-containing vaccines have led to fears regarding its safety.
In recent years there have been a number of events that have led to increasing concern over the safety of infant vaccination programmes. Suggested links between the MMR (measles, mumps and rubella) and autism and the hepatitis B vaccination and multiple sclerosis are just two of the issues causing such fears.
The study, published in Lancet Infectious Diseases, reviewed evidence of such adverse events, following the use of vaccines against diphtheria, tetanus and pertussis (DTP). The study focused on 35 reports, including three randomised trials, four semi-randomised trials and one cohort study. It looked at the incidence of erythema, induration, local reactions, collapse and convulsion and also the occurrence of crying and screaming. The review concluded that in both young and older children, alum-containing vaccines led to no serious and long-lasting adverse events.
Demonstrating the safety of alum is critical to securing patient confidence in such medications and driving and maintaining uptake, according to market analysts at Datamonitor. As DTP products currently form the mainstay of vaccine players' revenue, highlighting the safety of this adjuvant will prove even more important. This recent study should go some way towards alleviating concerns.
Vaccine preservatives, such as thimerosal, have also long been scrutinised and their safety remains an issue.
However, much progress has been made in removing or reducing thimerosal in vaccines. In the last few years the US Food and Drug Administration (FDA) has licensed new paediatric formulations of hepatitis B and diphtheria, tetanus and acellular pertussis (DTaP) vaccines. These include Merck & Co's Recombivax-HB (thimerosal free), GlaxoSmithKline's Engerix-B (trace thimerosal), and Aventis-Pasteur's Tripedia (trace thimerosal).