At least once a week, Dr. Joanne Langley or one of her colleagues in a Halifax pediatrics clinic carves 90 minutes or so out of a crammed schedule to try to persuade yet another set of anxious parents to vaccinate their baby against diseases that regularly used to sicken, maim and kill.

In Toronto, Marianna Ofner - a university professor with a PhD in epidemiology -- has gone to the effort and expense of travelling to the United States to buy single disease vaccines she can't get in Ontario. Ofner was determined to avoid exposing her young daughter to the combined measles, mumps and rubella vaccine that so frightens the parents Langley sees.

Such is the legacy of the research of British gastroenterologist Dr. Andrew Wakefield, whose purported discovery of a link between the so-called MMR vaccine and autism continues to haunt efforts to protect children against these and other vaccine-preventable diseases in North America, Britain and beyond.

The British body that governs physicians, the General Medical Council, begins a hearing Monday into allegations that Wakefield and two colleagues behaved unethically and dishonestly in conducting their research. The hearing, expected to last months, could result in the trio losing their medical licenses.

The voices of infectious diseases specialists and pediatricians display anger and dismay when the subject of Wakefield and his work comes up.

Dr. David Scheifele, a vaccine expert at B.C. Children's Hospital in Vancouver, dismisses Wakefield's research as "nonsense."

"It shouldn't have been published in Lancet," says Scheifele, referring to the prestigious British medical journal that ran Wakefield's study in 1998.

"It's very interesting how important the responsibility is to speak carefully about risk -- because one paper can just poison so much thinking," adds Langley, a pediatric infectious diseases specialist at Halifax's IWK Health Centre.

In the nearly 10 years since the Lancet publication, scads of studies costing untold millions of dollars have failed to corroborate the link Wakefield still insists exists. Scientific authorities such as the U.S. Institute of Medicine have flatly concluded that Wakefield and his coauthors were wrong.

"I actually feel enormously sad that this has been allowed to go on as long as it has. I think that there's been an enormous amount of wasted effort pursuing a theory that is based on flawed science," says Dr. Brian Ward, an infectious diseases expert at Montreal's McGill University who was approached by but declined to work with Wakefield.

"Gosh, if I were the parent of an autistic child and I were having trouble getting services for my child, those millions of dollars could have been so much better spent on real research or providing real services," Ward adds.

In 2004, 10 of Wakefield's 12 collaborators retracted the Lancet study.

"We wish to make it clear that in this paper no causal link was established between MMR vaccine and autism, as the data were insufficient," wrote the group. "However, the possibility of such a link was raised. Consequent events have had major implications for public health."

A 'fatal' conflict of interest

Indeed they have. At one point MMR vaccination rates sunk to 75 per cent in Britain, well below the 95 per cent authorities say is needed to keep these diseases from circulating. While the rate has since climbed to about 85 per cent, Britain continues to suffer outbreaks of these three diseases and to seed the diseases abroad. The mumps outbreak Nova Scotia and a few other provinces have been fighting since mid-winter seems to trace back to a case from Britain.

The Public Health Agency of Canada says MMR vaccination rates in this country hovered around the 95 per cent rate throughout the period from 1997 to 2004, though no data were collected from 1998 to 2001. Still, in Canada and in the United States, anecdotal reports from pediatricians -- and a perusal of Internet discussions dedicated to the issue -- show the fear sparked by Wakefield's work has taken root here too.

Shortly before publishing the retraction, Lancet editor Dr. Richard Horton declared Wakefield had a "fatal" conflict of interest that would have precluded publication, if the journal had been informed of it.

The doctor was doing paid research for a group of parents of autistic children who were trying to mount a class action suit against the makers of the MMR vaccine. Later it was revealed Wakefield had taken out a patent on a new vaccine while publicly challenging the safety of the existing one.

Despite the allegations of research improprieties, despite the mounds of studies refuting Wakefield's work, pediatricians continue to find themselves facing parents reluctant or unwilling to vaccinate infants against these diseases and others.

Fear can trump science, especially when babies are concerned.

Ofner, who specializes in the spread of hospital acquired infections, knows how to read and assess complex medical studies.

Her oldest child, a seven-year-old daughter, is autistic. The little girl was vaccinated with the MMR shots, which are given at about the age when autism's first symptoms are typically observed.

When Ofner's second daughter was born, she didn't want to take a chance with the combined vaccine, and arranged to purchase individual vaccines against the three diseases. Her second daughter was diagnosed with autism at 18 months. But a reappraisal when the girl was three revealed she no longer meets the criteria for autism.

"I'm totally pro-vaccination," Ofner insists.

"However, when it's your kid and there's a slight chance." she says, leaving the sentence unfinished.

She accepts that studies have proven the shot doesn't cause autism, but worries it might serve as a spark in a small subset of children with a genetic predisposition to the condition. She has a cousin with autism and believes coding for the condition may be contained in the genetic blueprints of one or both of her daughters.

"I've read everything. You know what? Honestly I don't know. So I went to my pediatrician and I said: I don't feel comfortable doing this," says Ofner, referring to vaccinating her youngest daughter with the MMR vaccine.

Still, she points to the experience of a friend who has two sons, both autistic.

"She vaccinated the first one and the second one she didn't. The second one is severe, the first one is mild," Ofner says, referring to where on the scale of autism the boys fall.

"So what's that mean?"