The lack of thoroughness is partly because government officials failed to make it a high priority.

Although there is some good research on childhood vaccines, it is overwhelmed by the bad. The public has been let down because the proper studies have not been done, according to experts.

Public health officials fear that the accusation will alter parents’ confidence in national vaccination programs. Many parents are already opting against the triple measles, mumps and rubella (MMR) vaccine after it was associated with autism and bowel disease.

Experts noted that while there is no evidence suggesting that any current vaccine is dangerous, studies on their risks and benefits are scarce and the information available is "simply inadequate."

Moreover, future vaccination programs will likely involve giving children up to seven vaccines at once. Because of this it is becoming more and more difficult to determine what problems may be due to an individual vaccine.

In Europe, plans for a Europe-wide electronic register of children's vaccine exposure that would allow scientists to investigate the risks and benefits of inoculations using data on thousands of participants may help to determine the origin of problems.

Though governments are generally reluctant to accept such systems, experts say that systems to monitor vaccines are needed urgently.

Telegraph October 27, 2002