Aluminium salts (potassium aluminium sulphate, aluminium sulphate, or aluminium hydroxide) have been used for decades in vaccine formulations as adjuvants (non-specific stimulators of the immune response), and in this role they are vital to the protective efficacy of vaccines. But aluminium has been blamed for side-effects in vaccine recipients, such as local reactions at the site of vaccination and a chronic progressive syndrome called macrophagic myofasciitis. However, replacing aluminium with another adjuvant would be a massive undertaking because all such vaccines would have to be tested in clinical trials and relicensed; besides, no obvious replacement is available.
After an exhaustive trawl of the medical literature for relevant studies, Jefferson and colleagues collected data for a meta-analysis from five published trials. The authors compared adverse events in two settings: vaccines containing aluminium hydroxide versus no adjuvant for children aged up to 18 months, and vaccines containing different types of aluminium versus no adjuvant in children aged 10-16 years. Although aluminium-containing vaccines were more likely than plain vaccines to cause erythema (redness) and induration (hardening of the skin) in young children, and local pain lasting up to 14 days in the older children, there was no evidence that the aluminium-containing vaccines were responsible for serious or long-lasting side-effects.
Jefferson and colleagues recommend-unusually, perhaps, for modern medicine-that no further research be done on this topic.
Contact: Dr. Tom Jefferson, Cochrane Vaccines Field, Via Adige 28a, 00061 Anguillara Sabazia, Rome, Italy. T/F) 39-06-999-00-989; E) toj1@aol.com .
The Lancet Infectious Diseases