Although aluminum salts have been used for decades to boost vaccine effectiveness, there have been reports linking them to various problems, including a progressive disorder involving muscle wasting and fatigue, according to a report in The Lancet Infectious Diseases medical journal.

Determining the safety of aluminum is important because replacing the compound would be a huge undertaking requiring numerous safety trials before new vaccines become available, the researchers note.

To investigate the safety of aluminum-containing DTP vaccines, Dr. Tom Jefferson, from Cochrane Vaccines Field in Rome, and colleagues reviewed eight studies that recorded patient outcomes following vaccination and the amount of aluminum in the vaccine.

Immunization with an aluminum-containing vaccine was tied to an increased risk of redness at the injection site in young children, and with prolonged local pain in older children. However, there was no evidence in either age group linking such vaccines to serious or lasting adverse effects.

"Despite a lack of good-quality evidence we do not recommend that any further research on this topic is undertaken," the authors conclude.