Vaccinations are key to protecting the lives of young children. Yet among all the common misunderstandings about medicine, one of the most prevalent - and the most dangerous - is the belief that too many childhood jabs will 'overload' the immune system.

Twenty years ago, before the MMR debacle, we would have welcomed any new immunisation that could protect children. But when the government announced its new vaccine programme last week, you would have thought from the tone of some press reports that British doctors were conducting an experiment in giving children lethal overdoses.

In fact, the opposite is true. The vaccines given to babies and toddlers enable the immune system to prime itself in the fight against dangerous infections. They work by introducing purified antigens, foreign bits of protein, into the body, which then trigger the production of antibodies so that when the child is exposed to the real disease, they will have the correct antibody response. A disease such as pneumococcal meningitis, which kills some 50 children a year, presents an overwhelming case for immunisation and will now be part of the package a child receives.

But, as we report today, scientists are concerned that thousands of parents may take the 'overload' theory seriously and choose not to have their children vaccinated. They point out that the number of antigens a child receives through vaccination has in fact fallen dramatically. In 1992, children would receive more than 3,000 antigens to fight eight diseases. They now get 56 to protect against 12 diseases.

If parents exclude their children from immunisation programmes the consequences could be fatal. Vaccination is an essential weapon in the fight against childhood disease and government and scientists must work together to get that message across.