A PBS Newshour series about autism that drew former host Robert MacNeil back to the show for the first time in sixteen years is also drawing heavy criticism.

Parts of the six-part “Autism Now” series, which launched on April 18, revive the widely refuted theory that vaccines cause the developmental disorder, which leads to the impairment of social and communications skills and generally appears in the first three years of a child’s life. Moreover, in a number of instances MacNeil flouts principles of thorough, transparent reporting.

“If it turns out to be MacNeil’s swan song, it’ll be an embarrassing coda to his career,” wrote Seth Mnookin on the blog for his recently published book, Panic Virus, which criticized those who encourage irrational fears about a connection between vaccines and autism.

In fact, there are things to commend about MacNeil’s series, such as Part Four and Part Five, which respectively highlight the need for more educational resources for autistic children and for more support for autistic adults. However, as a superb review by the Los Angeles Times’s James Rainey (who recently won the 2010 Bart Richards Award for Media Criticism) points out, “MacNeil distracts from the central power of the series when he allows a reintroduction” of the vaccine-autism canard:

In Part I of MacNeil’s series, which aired April 18, MacNeil let his daughter Alison [whose six-year-old son, Nick, has autism] raise the possibility of a connection between the shots the boy received at 15 months and his subsequent “shutdown.” In a later episode, two of four researchers interviewed by MacNeil leave open the possibility that some subset of children could be harmed by vaccines — though they acknowledge there is not yet any proof.

MacNeil immediately followed his daughter’s opening-night statement by telling the audience that “public health authorities say there is no scientifically valid evidence that vaccines cause autism,” a position he repeated during a later episode, when he added: “All epidemiological studies have proved negative.”

So one might ask the venerable newsman, now 80: Then why even raise the vaccine issue, especially without any meaningful caution to parents about the downsides of a failure to immunize? Experts say that the reduction in vaccination rates has led to increased incidence of measles, whooping cough and other diseases.

“We have not done a series about vaccines. We have done a series about autism,” MacNeil told Rainey by phone. “I think we put the issue in perspective. But to not even allow it to be mentioned would have been extraordinary. To not even mention it?”

Of course, MacNeil does much more than mention the theory. He emphasizes it. Indeed, every expert he interviews tells him there are probably multiple causes of autism. They also stress that each case may depend on a particular combination of risk factors that could be genetic, environmental (chemical toxins, infectious agents, etc.), or nutritional, among other things. Yet the only hypothesis that comes up more than once or receives any special consideration whatsoever is vaccines.

What seems to sway MacNeil is a supposed change of heart at the federal organization that monitors and advises about research related to autism spectrum disorder. According to MacNeil in Part Three of the NewsHour’s series:

Public health officials have steadily maintained that there is no valid science evidence of such a connection. All epidemiological studies have proved negative. But now, bowing to public opinion, the body that sets priorities in autism research, the Interagency [Autism] Coordinating Committee, has recommended studies to determine whether small subgroups might be more susceptible to environmental exposures, including vaccines.

MacNeil makes the same assertion in a promotional interview with a PBS colleague, Hari Sreenivasan, saying that the group “has just now, in March, recommended that research be done” on the alleged subgroup that are vulnerable to immunizations. But there are two big problems with these statements. First, beyond mentioning the committee’s recommendation, MacNeil provides absolutely no context about what types of studies should be pursued, how those studies should be designed, or where they would fit within the much, much larger fields of vaccine-safety and autism research.

Curtis Brainard is the editor of The Observatory, CJR's online critique of science and environment reporting. Follow him on Twitter @cbrainard.