When Max Sullivan was born two years ago, his father Paul, a 41-year-old IT consultant, and his accountant mother Karen, 34, were prepared for their first foray into parenthood.

"We bought the best pram we could, a Bugaboo. It's like a tank," says Paul.

"We checked toys were safe and bought stair-gates and caps for the corners of the tables for when he started walking.

"And when he was two months old we followed the doctor's orders and took him for his first set of immunisations: the five-in-one jab that combines the DPT - diphtheria, pertissus (whooping cough) and tetanus, polio and Hib (haemophilus influenzae type B) vaccines.

"We took him for boosters at three and four months, as instructed."

The couple were model parents. But then Paul and Karen received a letter inviting Max to have the new meningitis C jab.

"It seemed like too much to be giving such a tiny baby," says Paul.

"We started to look into it online and read reports of headaches and swollen arms to meningitis-like symptoms that have put some children in hospital.

"The nurse did call and try to persuade us but she couldn't provide us with hard facts about how safe it was and we decided to call things to a halt."

The couple chose to stop vaccinating their son and instead use a healthy diet to boost his immune system.

They claim they were "unnerved" by the uncertainty surrounding the effects that vaccinations can have on children, in the wake of the combined measles, mumps and rubella vaccination (MMR) scandal that controversially linked the triple jab to autism.

Max remains vulnerable to life-threatening diseases having not been vaccinated against meningitis C, pneumococcal - an infection that can lead to pneumonia or septicaemia - measles, mumps and rubella.

He will also not be given boosters to assure continued immunity to diphtheria, tetanus, whooping cough or polio.

"We believe there is a problem with vaccines in general - the MMR debate just put a spotlight on the issue," says Paul.

"I've heard stories from parents who believe that their child's asthma, skin allergies, eczema or autism has been triggered by immunisations.

"They've taken the mercury out of the jabs but I've read online that there's still aluminium in some.

"I accept science has made amazing progress in treating some very aggressive diseases, but injecting these things into a baby is instinctively wrong for me."

Thiomersal, a mercury-based preservative, was removed from inoculations in 2004.

The change was welcomed by anti-MMR campaigners who believed mercury in jabs was linked to developmental problems in children.

The evidence that thiomersal can harm the developing brain is contentious, with several studies producing conflicting reports.

The decision to remove it from new vaccines came after the World Health Organisation (WHO) said it should be avoided on a "precautionary" basis.

"Of course I have wrestled with this and wondered whether we're doing the right thing for Max," says Paul.

"Even if there's a small risk, it still feels like playing Russian roulette with your child's health.

"We'd rather take our chances with the diseases than potentially damage our son for the rest of his life.

"I had measles as a child and my sister had rubella. We're both OK.

"We're trying to give Max a healthy diet so he's got a good immune system.

"If Max did get measles I'd give him a boost with Vitamin C and Vitamin A from cod liver oil.

"If we have a second child, there will be no vaccinations at all."

Because diseases such as measles are infectious, it's a view that many parents will see as selfish.

But far from being alone in their concerns, the Sullivans are part of a growing number of middle-class parents ignoring NHS guidelines on vaccinations and doing things their own way.

For vaccination to work, however, enough of those in a community must be immunised against certain diseases so it becomes difficult for them to pass between those who have not been.

Diphtheria, for instance, has all but disappeared in the UK.

Fears that the MMR triple jab - introduced in the UK in 1988 - could lead to autism caused take-up to fall from more than 90 per cent in 1998 to less than 80 per cent two years ago, say the Health Protection Agency.

Currently, 81 per cent of children have the combined vaccine before they are two.

Last year, 971 cases of measles were reported in the UK, up 30 per cent in 12 months.

The disease claimed the life of a 14-year-old boy in 2006, the first death since 1992.

According to the WHO, more than half a million children under five die from measles every year - half the number claimed by the disease ten years ago, after successful vaccination programmes in developing countries.

In the UK, since the introduction of the MMR in 1988, the total number of infant deaths from the disease is four.

Layla Evans, 27, a music artist manager who lives in West London with her partner Sandy Rivera, 37, a musician, has spent £200 so far on immunising their four-month-old daughter Mya with single vaccines for polio, tetanus and diphtheria.

However, she has refused to give Mya the pertissus and Hib, meningitis C and BCG (tuberculosis) vaccines.

"I don't want to be pressurised to follow Government guidelines. I don't see why I should when there's nothing proven absolutely for every vaccination," says Layla.

"We waited until Mya was three months old before doing anything. By then she should have had the five-in-one shot but I felt she was too tiny.

"I've done a lot of research, mainly on the internet, and I'm doing what I think is the right thing for her.

"The things I didn't immunise her against are things I don't think there are 100 per cent effective vaccinations against, such as whooping cough."

Born and raised until the age of five in Belgium, like all children there Layla was vaccinated with individual shots.

She says her mother supports her choice not to give Mya certain jabs but admits many friends with children are concerned.

"Some have called me selfish, and even mad," she says. "But it's my baby and our lives not theirs. I'm not hurting her."

Anna Watson, 42, a full-time mother who lives in Kingston-upon-Thames with her partner Jamie Asher, 43, a book publisher, agrees.

Her son Sam, four, is partially immunised and her two-year-old daughter Katherine is not.

"I caved in to pressure from the doctors to start Sam's vaccinations at about five months even though I wasn't happy about it and he had the ones for diphtheria, tetanus and Hib," she explains.

"I had done a little research and felt very strongly that he shouldn't have the live polio vaccine or any containing mercury, so I stood my ground on those.

"Very shortly after, the Government announced it was withdrawing live polio and those containing mercury and it gave me a lot of confidence that I was on the right track."

As a result of her experiences, in January last year Anna decided to set up Arnica, a support network for parents with concerns about vaccinations.

Eight Arnica groups have formed around the UK since the network began, each with several hundred members.

More established online parent groups, Jabs and The Informed Parent, whose numbers swelled during the controversy around the MMR, have more than 3,000 members between them.

"There are hundreds of us now and we believe passionately about the health of our children," says Anna, a former primary-school teacher.

"We've got two nurses in our group who find their position difficult as they have to vaccinate other people's children when they haven't had their own done.

"We have doctors in our group who don't vaccinate their own children either."

Instead, there has been a return to traditional pre-vaccination methods of protecting child health.

"I look at keeping my children well with lots of fresh air, exercise, sleep, nutritious food and lots of happiness," says Anna.

"I like to support my children to get well by themselves because the body can do it and the more you intervene with vaccines and antibiotics you suppress the body's own immune system."

Anna is well aware many parents would think she is cavalier with the health of her children but she disagrees.

"I've been called selfish by doctors and health visitors.

"In fact, I'm more vigilant than most parents - I've chosen to educate myself about immunity and how to deal with diseases, rather than blindly hand over responsibility to the State or doctors."

Despite prevailing medical opinion, Dr Richard Halvorsen, a GP in Central London and author of The Truth About Vaccines, shares many parents' concerns about what he considers the most complex vaccination schedule in the world, where by the age of 15 months, babies receive 25 doses of the various vaccines.

"When the diphtheria vaccine was introduced and when the vaccination trials for whooping cough began, those diseases were killing thousands of children every year and it made sense to look at something quite radical to prevent them. What I'm saying is, hang on, let's just stop and think."

Allergy-related illnesses such asthma and eczema are rising - in Britain, up to a fifth of school-age children are affected - and there is an argument that vaccines are playing a part, says Dr Halvorsen.

Recent research, published in the US Journal Of Allergy And Clinical Immunology, found children who have their routine vaccinations delayed by two months or more cut their risk of asthma by half.

The study, based on health records of 14,000 children, found that 14 per cent of children who received their first shot of diphtheria, pertussis, tetanus vaccine at two months, developed asthma - compared with only 5.9 per cent of children who were vaccinated more than four months after the scheduled date.

In response to demand for a more pick-and-mix approach, Dr Halvorsen is opening a private clinic, Babyjabs, this spring.

It will offer a comprehensive selection of vaccines for all ages in single or small doses.

"There are many mothers who have not had their child immunised at all, but would if they had the ability to get some and not others, or to have them spaced out," says Dr Halvorsen.

"By offering this service we're going to up the immunisation rate."

GP Mike Fitzpatrick is based at a surgery in Hackney, East London where there have been more than 150 cases of measles.

"When you've a young baby, you're not always particularly rational about it," he says.

"You read things in the papers and you want to protect them, but the only real way is with vaccines.

"It's amazing how people's memories fade and how they now perceive measles as only a mild illness. Doctors will always remember the deaths."

- www.immunisation.nhs.uk, www.jabs.org.uk, www.arnica.org.uk, www.babyjabs.co.uk, www.informedparent.co.uk