The World Health Organisation hails vaccination and clean water as the two elements that have had the greatest impact on human health.

But while we all benefit from clean water in the UK, we don't all take advantage of vaccinations.

In fact, Labour MP Mary Creagh says vaccination rates are as low as 11 per cent in parts of London, and cases of measles, mumps and rubella are rising sharply'.

In a bid to get vaccination rates up to the 95 per cent recommended by the World Health Organisation, Creagh, who is in charge of Labour's health manifesto for the next election, has controversially proposed that children should not be allowed to start school unless they've had all their jabs.

The proposal has been strongly condemned by some health experts, including the chairman of the British Medical Association Dr Hamish Meldrum, who said forcing parents to have their children inoculated was morally and ethically dubious'.

Some parents simply don't want their kids to have vaccinations because they're scared the jabs may adversely affect their health, particularly after all the scare stories linking the MMR vaccine to autism in recent years.

However, the largest study published on the issue this year concluded that there was no link between the MMR jab and autism and certainly take-up of the vaccine is slowly recovering after plummeting in the late 1990s.

Cherie Blair, wife of the former prime minister, settled an old media query this week by revealing that her young son Leo did have the MMR jab at the height of the fears surrounding its safety.

The latest figures show that 85 per cent of two-year-olds received at least one dose of the MMR vaccine in 2006-07 and 75 per cent of children received a second recommended dose by the age of five. Levels of uptake for the five-in-one jab against tetanus, diphtheria, polio, whooping cough and Hib, was even higher at 94.1 per cent.

WHO insists vaccines are very safe', and side-effects are minor - especially when compared to the diseases they're designed to prevent.

It says serious complications occur rarely, illustrating this with the fact that severe allergic reactions happen in just one for every 100,000 doses of measles vaccine.However, some dispute the very safe' label, not least those parents who believe their children have been damaged by inoculations.

One such parent is Jackie Fletcher, whose completely normal' son Robert had the MMR vaccine at the age of 13 months. Ten days later he was rushed into hospital after having a severe seizure.

"He's never been the same child since," says Fletcher.

Robert, who's now 16, still has multiple seizures, can't walk or talk and is incontinent. He has the mental age of a 14-month-old child.

Fletcher, founder of the JABS support group for families who believe their children were harmed by vaccines, has struggled to get answers about what caused Robert's condition, but she blames the triple MMR vaccine.

She says: "We believe there may be some children who have a particular vulnerability to certain conditions. If more investigations were carried out, it could be worked out whether vaccines can trigger these conditions."

Fletcher believes parents should be shown the product sheet from the vaccine which lists ingredients, possible side-effects and so on, and should be offered single vaccines as well as the combined versions.

"Parents should be given accurate information so they can judge properly what their child is at risk from, and they need a full range of vaccine choices so they can select one according to their child's needs. But at the moment, it's just one size fits all."

She adds: "I'm not against vaccines - I recognise that certain diseases can be life-threatening and certain vaccines are valuable.

"But they need to be looked at on an individual basis."

Dr Richard Halvorsen also believes that certain vaccines are valuable - indeed, he offers them at his London Harley Street Babyjabs clinic.

"I'm pro appropriate vaccinations," he says, "but I'm not in favour of one or two of them and there are quite a few in which I think the benefit-risk ratio is probably fairly evenly balanced."

Halvorsen, author of the book The Truth About Vaccines, supports mass vaccination against diphtheria, tetanus, polio and measles.

But he believes the mumps and rubella elements of the MMR vaccine are not necessarily needed for the infants they're given to, and may be more appropriate given as single vaccines later in childhood, for example a rubella vaccine given to girls of childbearing age - as the illness can damage a foetus.

However, the Health Protection Agency (HPA) warns that fears about susceptibility shouldn't make parents complacent about vaccinations, even for what they may consider to be minor' ailments such as measles.

"If parents consider them to be mild infections it may be because they haven't witnessed the epidemics they can cause, the ease at which infections can spread between children and the seriousness of some of these infections," says HPA spokesperson Kate Swan.

"Measles is an infection that can kill. Before measles vaccination was introduced there were hundreds of thousands of cases of measles and, in some years, over a thousand deaths."

She adds: "By vaccinating your child you're helping to protect them against a potentially life-threatening infection. But you're also helping to achieve a good level of protection across the community. So by immunising your child you're effectively also protecting others."