The importance of immunisation was highlighted last week by the death of a London child from diphtheria. Though this respiratory disease once killed 4,000 people each year, most of them children, this was the UK's first fatal childhood case in 14 years. The reason for the decline is simple: an effective vaccine has essentially eliminated the threat.

The death, however, illustrates that vaccination rates are not as good as they might be. Only 94 per cent of children are given the combined jab that includes the diphtheria vaccine, and the take-up rate in London is only 86 per cent. National uptake of the triple vaccine against measles, mumps and rubella is 86 per cent, as confidence recovers after the unfounded autism scare. In some parts of London only 64 per cent of children receive MMR, and measles is making a comeback as a result.

This explains why a Labour MP and a senior doctor this week proposed new approaches to improving vaccine coverage. In the US, many states require children to be immunised against several conditions before they are allowed to attend publicly funded schools. In the political journal Fabian Review, Mary Creagh, who chairs Labour's public health manifesto group, suggested that a similar policy should be adopted here for MMR.

Sir Sandy Macara, a former chairman of the British Medical Association, backed a slightly different scheme. MMR, he said, should be linked to child benefit, so that families are penalised if they do not allow their children to have the jab.

Both ideas are well intentioned but misguided. There are good ethical and practical reasons why such policies would be wrong.

First, the proposals would punish children who are already disadvantaged by parental decisions not to vaccinate, not the mothers and fathers who take this irresponsible choice. As well as being exposed to the risk of measles, a serious disease that can kill or cause permanent disability, blameless children would be denied their right to education, or financial support that can lift families above the poverty line.

The policies are especially unjust as they would impact most greatly on under- privileged families, who are most likely to miss out on vaccination altogether. Middle-class MMR refuseniks tend at least to buy single vaccines for their offspring instead. But these are beyond the means of the poor, who also cannot afford private education or benefit cuts.

It is also questionable whether making certain vaccines effectively compulsory would build confidence and improve take-up, as Ms Creagh and Sir Sandy would wish. The reverse is probably more likely. While no vaccine is entirely risk-free, there is a wealth of data showing that the benefits of protection against serious diseases far outweigh the small hazards. Government coercion, however, will make many people instinctively suspicious about that.

The use of carrots, and especially the use of sticks, to encourage vaccination would give entirely the wrong impression about its value and safety. It would imply that parents cannot be trusted to see the advantages of vaccines and need their arms twisted to know what's good for them. It would certainly lead to a public outcry and civil disobedience, sometimes among families who would not otherwise question vaccination but dislike being ordered what to do.

It is right for politicians and public health experts to think creatively about ways of improving vaccine uptake.

Thinly veiled compulsion, however, should not be one of them. It is unfair, and it would sow needless doubts about safety. Immunisation is one of the great success stories of modern medicine. Coercion should not be necessary to tell it.

Mark Henderson is Science Editor of The Times

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